Originally Published: 23 SEP 21 11:56 ET

Updated: 23 SEP 21 14:01 ET

By Manu Raju, CNN Chief Congressional Correspondent

(CNN) -- House and Senate Democratic leaders say they've reached a deal with the Biden administration on options for paying for the Democrats' massive plan to expand the social safety net. But it quickly became clear that the deal lacked many specifics, needed to be sold to Congress and required ample negotiating to get broad consensus within their party.

At a news conference on Thursday with Treasury Secretary Janet Yellen, Senate Majority Leader Chuck Schumer and Speaker Nancy Pelosi said that they cut a deal on a "framework" to help pay for their plan. But there was still no agreement on a price tag for the proposal, which progressives and the White House want set at $3.5 trillion but will almost certainly be pared back at the insistence of moderates.

"This is not about a price tag," Pelosi said. "This is about what's in the bill."

But what's in the bill still hasn't been settled, as Democratic leaders and the White House furiously work to get key progressives and moderates behind an outline of an agreement by Monday. That's when the House is slated to take up the $1.2 trillion infrastructure plan that passed the Senate last month. But progressives have threatened to sink the plan if the vote moves ahead, worried they'll leverage with moderates over the larger Democratic only package.

Pelosi refused to say if the Monday would proceed.

"We take it one day at a time," Pelosi said.

What Democratic leaders hope is that enough of an agreement will be reached within the Democratic caucus by Monday to convince progressives to send the infrastructure package to President Joe Biden's desk. But it's far from clear whether that approach can succeed.

The agreement that Democratic leaders announced only involved a handful of players. A senior Democratic aide said it was cut by House and Senate Democratic leaders, the chairs of the House Ways and Means and Senate Finance committees. White House officials are meeting with key House and Senate moderates Thursday to talk about financing options.

"The White House, the House and the Senate have reached an agreement on a framework that will pay for any final negotiated agreement," Schumer said. "So, the revenue side of this, we have an agreement on."

Schumer later expanded on his announcement, telling reporters that "it's a menu of options" that will pay for whatever the final agreement is on the Democrats' sweeping social, economic package.

An aide to Sen. Kyrsten Sinema of Arizona, one such key moderate, told CNN that Sinema has not signed off on any tax proposal yet, and Schumer cannot afford to lose any of his members. Sinema has also previously criticized the $3.5 trillion price tag. And other key lawmakers had little idea what the deal entailed.

"I have no idea," said Senate Budget Chairman Bernie Sanders when asked about the agreement.

Paying for the proposal is only one of many issues Democrats face.

"What we said was the House, the Senate, and the White House came to an agreement on how we can go forward in a way to pay for this," Pelosi said. "We wanted to make sure it was paid for."

This story and headline have been updated to include additional developments Thursday.