Originally Published: 26 JUN 21 09:02 ET

Updated: 26 JUN 21 17:39 ET

By Kevin Liptak, Kaitlan Collins, Phil Mattingly and Lauren Fox, CNN

(CNN) -- At first glance, the bipartisan infrastructure deal that emerged this week seemed like a ripe opportunity for President Joe Biden to take a dig at his predecessor, whose attempts at focusing on roads and bridges often went awry.

"Welcome to infrastructure week!" read the notecard Biden carried Thursday to microphones set up outside the West Wing.

He nixed the joke. If Thursday marked anything, it was more like the start of a long infrastructure summer, on the back of a sort of infrastructure spring, the outcome of which remains uncertain even as Biden hails victory for his long-held faith in bipartisan compromise.

Already, Republicans are hardening in opposition to Biden's scheme of passing the $1 trillion infrastructure deal — which hasn't been written yet — alongside a much larger package containing the remainder of his agenda that will require only Democratic votes. And Biden set off a frenzy by confidently telling reporters he would not sign the bipartisan deal he had just negotiated unless he had the larger package on his desk, too. "If they don't come, I'm not signing," Biden said Thursday. "Real simple."

The uproar gained enough steam that by Saturday afternoon, Biden was forced to release a statement clarifying his pledge not to sign the bipartisan bill on infrastructure unless it came paired with a reconciliation proposal for "human infrastructure," writing that his comments "created the impression that I was issuing a veto threat on the very plan I had just agreed to, which was certainly not my intent."

"The bottom line is this: I gave my word to support the Infrastructure Plan, and that's what I intend to do. I intend to pursue the passage of that plan, which Democrats and Republicans agreed to on Thursday, with vigor."

The President's statement Saturday was the latest in a series of cleanup attempts from the White House seeking to stem defections from the bipartisan agreement. The move came hours before many of the Republicans who helped broker the deal, and were subsequently frustrated with Biden's Thursday comments, were set to appear on the Sunday morning talk shows where it's expected they would publicly air their irritation.

In a Friday afternoon conference call, "frustrations boiled" among Republican senators, according to a person familiar with the conversation, who said lawmakers were "dumbfounded" by White House explanations for Biden's approach.

The White House also looked to reassure its own party.

Concerned about spooking moderate Democrats he had just spent weeks cultivating, Biden's aides hastily scheduled a midday call with Democratic Arizona Sen. Kyrsten Sinema to reassure her of where Biden stood. The White House even took the unusual step of issuing a lengthy readout of their conversation, a practice typically reserved for foreign counterparts.

A senior administration official acknowledged they were attempting to walk back Biden's remarks, and directly tied his conversation with Sinema to that effort. While they believed his sentiment was accurate -- they want both deals passed in tandem -- his advisers acknowledged the tactic of demanding as much publicly was too forward and needed to be softened.

In their public comments, White House officials -- including press secretary Jen Psaki -- declined to directly reiterate Biden's threat of leaving the deal unsigned if the larger package doesn't materialize.

White House officials believe it has long been clear the two packages would move together and publicly scoffed at suggestions lawmakers were caught by surprise. But Biden's ultimatum did appear to test the durability of the agreement, leading the same aides who negotiated the deal to get back on the phone with lawmakers Friday who were balking. Aides stressed Biden's continued support for the deal and his plans to travel around the country selling its merits, according to a White House official.

Going forward, the White House plans to focus on selling the bipartisan bill instead of getting involved in the order of when Biden receives the legislation, letting Democratic leadership handle the timeline.

Some inside the White House believe the risky maneuvering was the only way Biden could secure enough Democratic support for the eventual $4 trillion reconciliation bill, a telling sign of the degree to which his party's divide is ever-present.

If the agreement falls apart, it could largely poison future opportunities for working across the aisle, particularly as midterm election season nears.

If he pulls it off, the two-track strategy would prove a striking show of legislative mastery for a career lawmaker whose presidency hinges on bringing together the progressive and moderate wings of his party. Aides said as much as Biden was invested in the substance of the deal, he was just as focused on the message it sent about the state of American government -- and the vindication it contained for his personal brand of politics.

Months of walking a tightrope ahead

It was a key ingredient for more than just Biden. Several senators in the bipartisan group that crafted the deal mentioned the need to show government could deliver as a driving force. In the Oval Office before Biden emerged with the group to announce the agreement, it was a central point of the conversation, one official said.

"People really felt committed to one another in this and I think everyone thought it was important for the country to send this signal that we could work together in this way," said Steve Ricchetti, counselor to the President and one of Biden's lead negotiators and closest advisors, in an interview.

After the deal was struck, Biden's victory lap took on an air of righteousness, claiming he'd proved his naysayers wrong. Behind the scenes, Biden frequently dismissed progressives who said he was wasting his time pursuing talks with Republicans, according to people familiar with the discussions, with the President claiming they knew little about how deals were struck in Washington.

But at best, neither bill will be ready for final passage until the fall, leaving weeks for potential pitfalls to throw off the carefully crafted political balance that the future of Biden's agenda is now contingent upon. Even if the deal ultimately falls apart, Biden's close advisers are still confident he'll get credit among voters for his public outreach to Republicans on the matter.

The tandem strategy flowed from both political necessity and the President's own inclination. As a long-time legislator with close relationships in both parties, Biden takes pride in his ability to cross the aisle and considers it a balm for a polarized nation. He also has ambitious policy goals, a mostly hostile Republican opposition and ultra-thin Democratic congressional majorities behind him, limiting his available strategic paths.

From the beginning, Biden's senior aides acknowledged the two-track strategy might not work. But they stuck with it deep into his fifth month, even as liberal Democrats pressed him to cut it short for fear that Republican negotiators real aim was a crippling delay.

Even as talks with an initial group of six Republican senators began to falter, Biden's advisers were eyeing other possible lawmakers or groups to continue their pursuit.

One of those groups, led by Sinema and Ohio Republican Sen. Rob Portman, had quietly been discussing a possible path forward for weeks. They carried with them a level of trust, and -- to some degree -- success based on an effort to unlock a long-stalled Covid relief package at the end of 2020. When Biden officially ended the talks with Republicans, led by Sen. Shelley Moore Capito, he placed a call directly to Sinema shortly after.

"The President and the team tried to keep as many avenues to success open in this kind of bipartisan structure in the hope that we could keep getting closer and closer," Ricchetti said.

The White House strategy appeared to work Thursday when Biden announced the bipartisan deal. Even after Republican parties to the deal subsequently grew skittish, Biden aides expressed confidence it would hold, despite what one senior official called "faux outrage" over the second part of a publicly articulated Biden strategy they'd known all along.

"They will have to vote against their own deal," one senior official said. "What they cannot say is that the infrastructure bill is too big, or a waste, or pork, or whatever. Look, in the end, I think it will stick together."

The official added: "For us, every step forward is a step forward. It's never a straight line."

At least on Thursday afternoon, the image of Biden surrounded by Republican and Democratic senators -- none wearing masks -- declaring victory on a major legislative agreement seemed vindication for a President whose campaign pitch rested in large part on ending the pandemic and uniting the country.

Standing in a spot usually reserved for visiting lawmakers or out-of-town dignitaries, not presidents, Biden harkened back to his own days as a senator, when he was the one emerging from the White House to recount meetings with successive commanders in chief. The President insisted on walking out with the senators, aides said, mindful of the image that he believed told a story of unity.

"This reminds me of the days we used to get an awful lot done up at the United States Congress," he said, crowded by senators whose ranks he left more than a decade ago.

"A lot of us go back a long way, where we're used to doing one thing: Give each other our word and that's the end. Nobody questions it," he went on. "They have my word, I'll stick with what they proposed, and they've given me their word as well. So, where I come from, that's good enough for me."

'Nobody is going to get everything they want'

Whether those rules still apply in today's Washington will be tested as White House aides and Senate staff put the bipartisan proposal into an actual bill, and as Democrats sweep up what wasn't included to put in the massive budget package.

White House aides remained convinced even the existence of a bipartisan bill in the current hyper-polarized environment was a sign that Biden's insistence on consensus was not misplaced.

"I think if you have said to anybody in my party a year ago that we would be talking about a $1.2 trillion infrastructure package, that they would have been pretty darn happy," said Anita Dunn, a senior adviser. "I think once they've look at the details of this, they'll see a lot to be for. You know, nobody is going to get everything they want when you have to compromise."

Yet Republicans grumbled that Biden would be getting everything he wanted, should his two-part strategy work, and many GOP senators were reluctant to lend a hand to a presidential victory.

The bipartisan group's efforts had begun in earnest months earlier with one-off meetings between colleagues. Lawmakers managed early to keep their work out of headlines, allowing the White House negotiation with Capito to play out.

Capito and a key Democrat in the bipartisan group, fellow West Virginian Sen. Joe Manchin, were close, and members thought it wise to give the White House the room it needed to try and make a deal with key Republicans who had top roles on the relevant committees.

That effort collapsed right before Biden left for his first overseas trip to Europe, undercutting his efforts at bipartisanship just as he was set to debut on the world stage. He left behind key staffers, including chief of staff Ron Klain, to try and salvage a deal.

The bipartisan group, working until this point in the background, saw an opportunity to step into the spotlight and finish their work.

"We aren't just a hot mess here"

Biden had a message for his senior team soon after he returned from the nine-day, high stakes diplomatic trip across Europe, according to multiple officials: He was ready to accelerate the process toward making a bipartisan deal.

He'd been briefed on the status of the group's work, which had sped up while he was overseas, and thought things were headed in the right direction on the policy side. The opportunity to clinch an agreement, one pursued with no success by a few of his predecessors and still crucial to unlocking the full scale of his economic agenda, was something he didn't want to pass up.

It was a message Biden's negotiating team delivered to the group of senators on Monday. They weren't authorized to strike a deal, and there was still significant work to be done with major differences that needed to be reconciled. But the signal was clear: Biden was ready to make it work.

Biden's team -- including Ricchetti, one of his longest serving advisers; Brian Deese, the National Economic Council director; and Louisa Terrell, Biden's legislative affairs chief -- were committed to be on Capitol Hill as the talks played out. A potential late-week meeting with Biden was dangled should negotiators near a deal -- something the President eagerly awaited, officials said.

Yet after a series of meeting Tuesday, there was little progress. South Dakota Sen. John Thune, the Republican whip, told reporters the talks had yielded little forward momentum, and members involved conceded afterward the sessions were not moving quickly enough to yield a deal.

One official acknowledged it had reached a point where there were real questions about whether key differences could be reconciled, with both sides ardently defending their redlines against efforts to massage them open.

On Wednesday afternoon, the attitude began to shift. Lawmakers -- on the cusp of a two-week recess -- marched into the Strom Thurmond room at the Capitol for a meeting with White House officials aware that if a deal didn't come together in a matter of hours, it was possible it never would.

That morning, a bipartisan group of lawmakers attended the memorial service for Sen. John Warner, a Republican from Virginia who had built a legacy of cutting hard deals in the Senate. A centrist Republican, he often crossed his party on issues of gun rights and abortion. In 2014, he was part of a group of more than a dozen senators who helped preserve the filibuster on judicial nominees.

"In the battle for the soul of America today, John Warner is a reminder of what we can do when we come together as one nation," Biden said in his eulogy at the Washington National Cathedral.

Sen. Mark Warner, a Democrat from Virginia who had been in the room for much of the negotiations trying to represent the White House's positions, told CNN that at a few moments he thought about packing up and leaving the room.

"There were three or four times where I thought we were literally minutes away in terms of the frustration level on both sides," Warner said.

After the memorial service that morning, he walked into talks Wednesday afternoon with a new sense of patience.

"What would John Warner do?" Warner said he asked himself. "Well, John Warner wouldn't have packed up his books, so I opened up my notebook again and tucked back in. I thought about it. It was vivid in my mind."

White House officials, frustrated and down about prospects just one day prior, recognized a different tone -- and impetus to find a path forward.

"Sometimes deals, before they congeal, spread apart a little bit and then they come back together," one official said.

Within hours a framework was clinched.

Since announcing their agreement, the bipartisan group's work has come under fire, with progressives arguing the package is "paltry" and Republican leaders signaling the bill could be in trouble if Democrats hold firm to their promise not to pass the bill out of both chambers without a Democratic-only infrastructure bill riding alongside it.

"We are going to have to sell it," Sen. Jon Tester, a Democrat from Montana, told reporters. "Is it going to be as much as some people wanted? No. Is it going to be more than other people wanted? Yeah."

"It shows the world that we aren't just a hot mess here," Tester said.

That, of course, remained very much an open question as the senators returned home for a two-week recess and Biden headed off into the warm summer sun for a weekend at Camp David.