By Gregory Krieg, Eric Bradner and Dan Merica, CNN

(CNN) -- The Republican Party is all in on President Donald Trump. Now, with one week before the midterm elections, he's going all out for them.

Undeterred by the string of deadly horrors that might have paused another president in campaign mode, Trump is stumping relentlessly in a late push to save the GOP House and Senate majorities, using rallies and Twitter to stoke fear over a group of migrants nearly 1,000 miles from the US border while boosting false claims from Republican candidates about their efforts to tear up one of Obamacare's most popular features.

Trump will travel to Pittsburgh on Tuesday to show support for the community after a gunman killed 11 congregants at a synagogue in the deadliest anti-Semitic attack in US history. On Wednesday, he kicks off a swing of 11 rallies in six days.

Operatives in both parties and nonpartisan analysts have coalesced around a view that Republicans appear likely to benefit from a favorable map and keep control of the Senate, perhaps even padding their majority. But the GOP's grip on the House is slipping. After two years of unified Republican rule, the Democratic Party's base is rallying around a crop of first time candidates and now has a variety of potential paths to winning the 23 seats they need to regain a measure of control on Capitol Hill.

Trump has said that he shouldn't be blamed for a Republican midterm wipeout, but his travel schedule this week -- and the $22 million in transfers his re-election campaign has made to the Republican National Committee this cycle -- suggests he knows better. That even beyond pride, he has a lot to lose on Election Day. A "blue wave" on November 6 would immediately sink Trump's more ambitious political plans while exposing his administration to the kind of oversight Republican lawmakers have largely forsaken.

"I'm not on the ticket, but I am on the ticket because this is also a referendum about me," Trump said at a rally earlier this month in Mississippi. "I want you to vote. Pretend I'm on the ballot."

Republicans triage in House races

Democratic House candidates are entering the stretch run with momentum -- in the polls and the bank. Fundraising numbers, especially from small dollar donors, are through the roof. Grassroots liberal groups are organizing new and increasingly sophisticated mass voter drives. From the House to the governor's mansions in Florida and Georgia, offices held for a generation by Republicans are now considered either toss-ups or leaning in favor of Democratic challengers. GOP campaign arms are using the last few days before the election to shore up or rescue those old strongholds, while Democrats are pressing their advantage in places like Orange County, California, a series of suburban districts around Philadelphia, New York and New Jersey, and a trio of flippable Iowa congressional districts.

Outside Richmond in Virginia's 7th Congressional District, which Trump won by more than six percentage points in 2016, the Tea Party representative who ousted former House Republican majority leader Eric Cantor in a 2014 primary is now stuck in a dead heat with Democrat Abigail Spanberger. Rep. Dave Brat, who was on the short end of one the season's most viral moments when Spanberger lashed out at him at the end of a debate for misleading voters about her positions, has been outraised by the former CIA operative by a 2-to-1 margin.

And Brat might be one of the lucky ones.

He still has the backing of the Congressional Leadership Fund, the outside group aligned with retiring House Speaker Paul Ryan. But both the CLF and the National Republican Congressional Committee are in triage mode as Election Day nears. Colorado Rep. Mike Coffman, Pennsylvania Rep. Keith Rothfus, Michigan Rep. Mike Bishop and Kansas Rep. Kevin Yoder are among a growing collection of Republicans who have been discussed as lost causes -- an acknowledgment from national GOP leaders that there are some seats the party cannot hold.

But the Democrats are not without headaches of their own, particularly in the battle for Senate control. New Jersey Sen. Bob Menendez, whose popularity took a hit even after the corruption charges against him were dismissed in January, is now clinging to a narrower-than-expected lead in the polls over big-spending Republican challenger Bob Hugin. National Democrats are now sinking millions of dollars into a race that should have been a given — money that might have otherwise been earmarked for endangered incumbents in states Trump didn't lose by 14 percentage points in 2016.

Red states like North Dakota, where incumbent Sen. Heidi Heitkamp has consistently trailed her Republican opponent in polling. But also in closer contests, where Democrats like Missouri Sen. Claire McCaskill and Indiana Sen. Joe Donnelly are trying to cut against the grain and win over voters who broke decisively for Trump in 2016. Republicans have made those senators' no votes against Supreme Court Justice Brett Kavanaugh a major issue in the final weeks of the campaign in hopes of ginning up their base.

If Democrats fail to take control of the Senate, any Supreme Court vacancy in 2019 or 2020 would likely be filled by Trump.

Trump's closing message

As varied as the campaigns and candidates may be, nearly all of the most competitive races of 2018 have been linked by a common thread: Democratic pledges to expand health care coverage and protect popular programs like Medicare, Medicaid and Social Security while putting a check on Trump's power.

The GOP message has been more varied but has mostly followed the President's lead: a smorgasbord of fear-mongering over immigration; outright lies or misdirection when it comes to the party's efforts to endanger protections for people with pre-existing conditions as part of their push to unwind Obamacare; and more general warnings that Democratic victories in November would empower a liberal "mob." With seven days to go and Trump planning nearly a dozen rallies in that time, the list still has room to grow.

The Republicans' scattershot approach was on full display Monday morning, as Trump veered from an attack on the media, calling an African American Democratic candidate a "thief" and continuing an escalating barrage of inciting claims about "the caravan" -- a group of migrants whose movements have become a catch-all for his anti-immigrant messaging.

"Many Gang Members and some very bad people are mixed into the Caravan heading to our Southern Border. Please go back, you will not be admitted into the United States unless you go through the legal process. This is an invasion of our Country and our Military is waiting for you!," he tweeted.

In an interview with Axios published Tuesday, Trump said he would end birthright citizenship through an executive order, a move that would almost certainly draw legal challenges over its constitutionality.

Trump is also reportedly considering a speech on immigration this week to further gin up his base -- and drive them to the polls. And just days ahead of the elections, Trump ordered 5,200 troops and some military equipment to the southern border to, ostensibly, confront a group of migrants still 900 miles and weeks away from the US.

Democrats, meanwhile, say Trump's incendiary rhetoric could further alienate moderate Republicans -- particularly women in the suburbs.

"Our President even tried to tie terrorists from the Middle East with the caravan. It's like bringing up all of these buzzwords that stir up a frenzy in their base," said Kim Schrier, the Democratic congressional candidate in Washington's toss-up 8th District race -- a contest where spending has topped $25 million -- in an interview Sunday after a speech to dozens of her campaign's volunteers in the suburbs of Seattle.

"We all teach our kids that we're better than this," Schrier said. "That kind of rhetoric is unacceptable, and I'm hoping it brings a lot of those people out, saying, 'No. We don't tolerate this divisiveness and whipping up a frenzy.'"

The prospect of a Democratic House majority putting a check on Trump, she said, has resonated with suburban Republican women.

"I think a lot of them voted somewhat reluctantly for our President and would like to see some brakes on the rhetoric," Schrier said.

Trump will hit those nasty notes, live and in-person, at a series of rallies this week, which are currently scheduled for Florida, Missouri and West Virginia. Another stop, in Montana, could also be added to the itinerary.

His visit to Fort Myers, Florida, on Wednesday will mark his first time in the state since the arrest of Cesar Sayoc Jr., an ardent Trump supporter who allegedly targeted leading Democrats, including former President Barack Obama and Hillary Clinton, former intelligence officials and the news media with a series of mail bombs.

The rally will feature gubernatorial candidate Ron DeSantis and Gov. Rick Scott, who's in a tight race to unseat Democratic Sen. Bill Nelson. On Monday morning, Trump offered a preview of what's in store for the week when he called Tallahassee Mayor Andrew Gillum, the Democrat vying to become the state's first African American governor, "a thief." The comment sparked an instant backlash from Democrats, including billionaire donor Tom Steyer's group, which described the attack as "another racist dog-whistle meant to stir up his base because he knows DeSantis is behind." (Gillum led DeSantis by double-digits in a recent CNN poll.)

In October alone, Trump has visited 16 states --- Tennessee, Mississippi, Minnesota, Kansas, Iowa, Pennsylvania, Ohio, Kentucky, Montana, Arizona, Nevada, Texas, Wisconsin, North Carolina, Indiana and Illinois --- for political rallies.

And even as Democrats have sought to localize many of the key races in 2018 by largely ignoring Trump in paid ads, a number of campaigns and state parties have brought in some of the party's biggest national names to boost candidates in close or high-profile races make their closing arguments to voters.

In just the last weekend, around a dozen rumored 2020 Democratic presidential players made appearances in key states.

Vermont Sen. Bernie Sanders this weekend concluded a 9-day, 9-state swing in California. New Jersey Sen. Cory Booker has been up and down the trail, stumping in New Hampshire this weekend while former Massachusetts Gov. Deval Patrick rallied Democrats in South Carolina. Former President Barack Obama headlined events in Wisconsin and Michigan on Friday, while former Vice President Joe Biden stumped with Democrats in Connecticut ahead of his first 2018 trip to Iowa on Tuesday. California Sen. Kamala Harris has been making the rounds in Florida.

"We cannot look up ten days from now and have any regrets about what we could have done," Harris said to a group of Gillum supporters on Sunday. Someone interrupted her. She had the number wrong. Harris turned a wry smile and corrected herself: "I'm losing track," she said. "See, that's even fewer days to get out there!"