Republicans are scrambling to save suddenly vulnerable candidates in congressional districts that President Trump won in 2016, as Democrats have charged deeper into conservative strongholds in their bid to win the House.

On Tuesday, the National Republican Congressional Committee plans to launch an ad campaign in a South Carolina district that Trump carried by 13 percentage points, while House Speaker Paul D. Ryan (R-Wis.) intends to campaign for a Kentucky incumbent in a district that went to Trump by 15 points.

The last-minute moves follow decisions by Republican groups to toss political lifelines to House candidates in Georgia, Florida, Virginia and Washington state, all in districts where Trump was victorious.

Republicans are weighed down by an unpopular president, and the maneuvering reflects the challenging map that has forced GOP leaders to triage their candidates ahead of the Nov. 6 vote. Democrats are favored to win the House majority, according to nonpartisan analysts. They need a net gain of 23 seats.

Republicans believed the contentious confirmation of Supreme Court Justice Brett M. Kavanaugh and concerns about the migrant caravan headed toward the U.S.-Mexico border would energize voters in conservative districts. Protests of Kavanaugh fueled their attacks casting Democrats as an angry mob.

But now some worry that the power of those arguments will fade over time, particularly as Trump and his allies face criticism in the wake of the deadly massacre Saturday at a Pittsburgh synagogue and mail bombs sent to prominent Democrats, liberal donors Tom Steyer and George Soros, and CNN. Critics have accused Trump and some backers of fostering an environment for far-right extremism.

The past week “probably reminds everybody that the rhetoric is overheated on both sides. So to that degree, it takes a little steam out of the Republicans’ argument,” said Rep. Tom Cole (R-
Okla.), a Ryan ally.

As for the House map, Cole said there is no question that “if you’re a Democrat, you prefer a battlefield that’s expanding at the end.” He added, “To some degree, they have that.”

Republicans hold 25 districts that Hillary Clinton won in 2016, giving Democrats ample space to capi­tal­ize on anger with Trump and his party as they pursue the majority. They have also pressed Republicans on redder turf.

Ryan will be in Kentucky on Tuesday to campaign for Rep. Garland “Andy” Barr, whose 6th District stretches from Lexington to more rural areas. Former fighter pilot Amy McGrath has given Democrats hope of flipping the seat, despite the district’s naturally conservative tilt.

Meanwhile, the NRCC plans to launch ads Tuesday in South Carolina’s 1st District, an area along the coast including Charleston that has leaned conservative in recent federal elections. But Republican nominee Katie Arrington has had trouble putting away her Democratic opponent, Joe Cunningham.

Arrington, who defeated Rep. Mark Sanford in a primary defined by her support for Trump and the incumbent’s criticism of the president, has lost some GOP support to Cunningham, whose slogan is “Lowcountry over party” and who casts himself as a moderate.

Last week, a Republican mayor who endorsed Cunningham released audio of a conversation with Arrington in which she warned him that he’d taken his city “off the seat at the table” with his decision. She told the Charleston Post and Courier that she was talking about offshore drilling; he said it sounded like a broader political threat.

In an ad that started Monday, Arrington uses footage of the migrant caravan to warn against a Democratic Congress favoring “open borders” and “undermining law enforcement.” In his own ad, Cunningham says that “politics shouldn’t be seen as good or evil, tearing one another down.”

Democrats argue that their focus on health care, and drawing attention to how Republicans have tried to shred the Affordable Care Act and its protections for people with preexisting medical conditions, will prove more effective than the GOP’s immigration-based attacks.

“They’re working on fringe issues,” said Rep. Mark Pocan (Wis.), a member of the Democratic Congressional Campaign Committee leadership. “You know, there is no great threat of a caravan of transgender, Nancy Pelosi supporters that people are afraid of. And yet, you know, those are kind of the top issues they do, right? The fear issues.”

Republicans have pointed to Democratic retreats in key districts in Nebraska and Minnesota, and developments elsewhere, as signs that a massive blue wave many on the other side have hoped for is unlikely. Still, the GOP is nervously watching seats in areas that once looked safe.

In Virginia’s 5th District, the main House GOP super PAC went up on television for the first time last week. The Congressional Leadership Fund ad sought to help distillery owner Denver Riggleman (R) against journalist Leslie Cockburn (D) in a sprawling district that includes rural areas and the college town of Charlottesville. Trump won there by 11 points.

In Virginia’s 7th District, which Trump also carried, a new poll released Monday showed more possible trouble. The survey from the Wason Center for Public Policy at Christopher Newport University showed 46 percent of likely voters picking Democrat Abigail Spanberger and 45 percent choosing Republican Rep. Dave Brat.

The NRCC also hit the airwaves for the first time last week in Georgia’s 6th District in the Atlanta suburbs, where Democrat Lucy McBath has received help from well-funded gun control groups. Trump narrowly won the district.

“We’re not trying to cover the spread,” said NRCC communications director Matt Gorman. “We’re looking at victories.” He added: “The name of the game is volatility. And we’ve seen it on both sides.”

Democrats have raised huge sums of money, prompting Republicans to warn about a “green wave” of Democratic dollars, even in districts where the GOP has established a strong presence.

McBath started the final weeks of the campaign with $565,000 in her account; her Republican opponent, Rep. Karen Handel, had $402,000 left to spend.

The NRCC hit the airwaves for the first time last week in Washington’s 3rd District in the southwest corner of the state. Trump won there by seven points. Democrat Carolyn Long capitalized on a strong primary vote by outraising Republican Rep. Jaime Herrera Beutler by nearly $1 million.

Even in Florida’s 18th District, where Trump won by nine points and Rep. Brian Mast outraised his Democratic challenger, former diplomat Lauren Baer, Republicans are not taking any chances. The NRCC went up with an ad in the district that stretches north from Palm Beach County last week.

Mike DeBonis contributed to this report.