But behind the scenes, an all-out war between the party establishment and conservative base is breaking out -- in the halls of Congress, the fight for control of the Senate and in battleground states -- all threatening the GOP's chances of winning this fall.
Conservative insurgents in key Senate races are throwing their full-fledged support behind Donald Trump, hoping to foment anger at incumbent Republicans worried that embracing the controversial nominee too tightly could alienate swing voters.
Across the Capitol, a bloc of outspoken conservatives in the House Freedom Caucus is furious at the party leadership after the surprising ouster this week of a leader of the group, Kansas Rep. Tim Huelskamp, at the hands of a moderate candidate backed by well-funded groups linked to the party establishment. Conservatives are already plotting retribution, with some privately warning that House Speaker Paul Ryan could face a revolt from the right.
"Clearly the war continues," Huelskamp told CNN Wednesday. "The establishment never sleeps. They spend more time going after conservatives than going after Hillary Clinton. It was about sending a message, and the message is this: 'They came after me to get a scalp.'"
And GOP leaders are irritated at Trump for picking what they believe was an unnecessary fight with two prominent Republicans -- Ryan and Sen. John McCain -- just as the party was trying to train its focus on Clinton.
"If he wastes time settling scores, or responding to what he thinks to be criticism, then you're just wasting an opportunity to deliver a message," said Rep. Tom Cole of Oklahoma, an ally of Ryan's. "Don't waste your time commenting on the Republicans."
The ill-will between the base and the leadership has been growing since the rise of the tea party in 2010, culminating with the nomination of Trump on the backs of voters who feel betrayed by party leaders. And in the 2016 campaign, primary challengers in key Senate battlegrounds are seeking to align themselves with Trump in order to attack GOP incumbents who are struggling to support the GOP nominee's brand of Republicanism.
"What we are seeing here is the Trump wave," said Kelli Ward, a former state senator seeking to overtake McCain in the state's primary later this month. "The tsunami of anti-Trump sentiment is now crashing over so many people who have been in Washington for way too long."
Yet vulnerable Republicans in tough reelection races are finding new ways to distance themselves from Trump, including Colorado Rep. Mike Coffman, who released an ad Thursday saying of Trump, "I don't care for him much."
Primary foes seize on Trump's appeal to base
Long-shot primary challengers across the country are trying to latch onto Trump's appeal with the right. In Wisconsin, businessman Paul Nehlen has been sharply critical of Ryan, accusing him of undermining the party's nominee by his repeated criticisms. In Florida, businessman Carlos Beruff says he'll pump millions behind an ad questioning Sen. Marco Rubio's loyalty to Trump.
And in Arizona, Ward says she's actively lobbying for a Trump endorsement -- even going so far as urging Jeff DeWit, the Arizona chairman of Trump's campaign, to "put in the good word" for her to win the nominee's backing.
"I think I can be very, very helpful to Mr. Trump's campaign as well," Ward said. "He needs those kinds of surrogates and people who have been fighting for him."
McCain, who was unavailable for an interview Wednesday, supports Trump because he won the Republican nomination, including carrying Arizona with nearly 50% of the vote in the March primary. But in the aftermath of McCain's scathing rebuke of Trump for his battle with a Gold Star family of Muslim faith, the GOP nominee issued a stunning rebuke of the veteran Arizona senator and refused to endorse him in his primary.
"Look at John McCain: He can't get himself to vigorously support Trump," Ward said. "He just can't do it."
Ward's strategy is similar to Beruff's, the businessman in Florida who is trying to mount an upset against Rubio, who dropped out of the presidential nominating contest after losing his home state to Trump in March.
Beruff said he is investing "a couple million" dollars behind an ad promoting his support of Trump.
"Why does Marco Rubio refuse to support Donald Trump?" the announcer says in the ad.
Rubio, who is the heavy favorite headed into the August primary, is ignoring Beruff's attacks. And Rubio has aligned himself with Trump as of late, appearing in a video on behalf of the nominee at the GOP convention last month and also appealing to voters to elect Trump, saying recently, "We have to make sure Donald wins this election."
That's a far cry from the presidential primary, when Rubio promised to drive across the country in his pickup truck to stop Trump, warning the businessman would destroy the conservative movement and is a "con artist" who shouldn't have access to the nuclear codes.
"It's a tepid endorsement," Beruff told CNN Wednesday. "I think (Rubio's) a closet Hillary supporter. If Hillary wins, he's positioned to run for president in four years."
Conservatives plot recourse after Huelskamp loss
On Capitol Hill, GOP leaders have their own problems with House conservatives in the aftermath of Huelskamp's loss. Some point the finger at Ryan and other top GOP leaders for working against Huelskamp, a conservative agitator who sought former Speaker John Boehner's ouster and was defeated Tuesday by Dr. Roger Marshall in his primary.
A flurry of phone calls are happening behind the scenes Wednesday about next steps, conservative lawmakers say.
"How the speaker responds to this in the next week or two will have major implications in terms of future speaker races," one conservative warned in an interview with CNN.
House Freedom Caucus Chairman Jim Jordan, R-Ohio, issued a tough statement Wednesday morning, slamming his own leadership, saying while they should be uniting to run against the Clinton, "the House Republican leadership's opposition to Tim Huelskamp significantly damaged the ability of House Republicans to do that."
GOP leaders deny working to defeat one of their own, but Huelksamp said they didn't help him.
"He gave me no help pretty clearly," Huelksamp said of Ryan.
While House conservatives are directing their ire at Ryan and other leaders, the Kansas GOP primary was driven mostly by a battle between outside groups flexing their muscle. The Kansas Farm Bureau and the Ricketts family, which donates to high profile races, backed Marshall because of Huelskamp's combative record, while another prominent Republican donor family, the Koch brothers, joined with the conservative Club for Growth to support Huelskamp.
"They are trying to silence conservatives," Huelskamp said.
During his three terms in the House, Huelskamp frequently tangled with top GOP leaders. Boehner stripped him of his post on the House Agriculture Committee in 2012 for his regular breaks on major votes, which ultimately hurt him in his race. Agriculture groups and the U.S. Chamber of Commerce attacked Huelskamp, whose own family had deep farming ties, for voting against the farm bill and losing a key post that the district employers viewed as essential.
Allies of Huelskamp told CNN that Ryan made it known he wanted to see the Kansas Republican rejoin the committee and urged the steering committee that makes those assignments to address the issue, even though he couldn't guarantee the spot. But that didn't happen before the primary. Making matters worse, several GOP members told CNN that Ryan's position was never clear publicly and confusion over the issue only helped Marshall and his supporters to paint Huelskamp as out of step.
In early July, the speaker said "I've long thought Kansas should be represented on the House Committee on Agriculture. Tim Huelskamp has the kind of background that could serve the state well on the Ag Committee" but he also noted that committee slots would be decided by GOP members who vote on those assignments at the end of the year.
In a phone interview with CNN, Jordan said "it's a sad day." And without naming specific GOP leaders, Jordan said "they created this" because they gave Huelskamp's opponent an issue to use against him since he lost his seat on the Agriculture committee.
North Carolina Rep. Mark Meadows, another member of the House Freedom Caucus, said: "The biggest concern: Is this going to be the new norm? When we have groups that typically support conservative members group getting involved in a real distortion of voting records and trying to influence a primary."
No one is reporting active involvement of Ryan and other leaders to defeat Huelskamp, but Meadows said, "The real silence of leadership individuals on behalf of a sitting member of Congress was probably more of a concern."