The impact of likely having Trump at the top of the ballot come November is already being used as a weapon in some races, and apparently has at least one senior Republican concerned about his re-election.
"Some Republicans will come back to the fold, hold their noses, and vote, but many won't," said James Campbell, a professor of political science at the University at Buffalo.
"I suspect that there will be a good number who will go to the polls and just skip the presidential contest, but there will be many who will just sit out the election completely and this will hurt every Republican candidate," he added.
According to a recording from a private fundraiser that was held in April and obtained by ABC News, Arizona Sen. John McCain expressed concerns about how if Trump is selected as the Republican nominee, that could cause him problems in his re-election campaign.
"If there is a Donald Trump at the top of the ticket, and you’re in Arizona with over 30 percent of the vote being Hispanic vote, I have no doubt that this may be the race of my life," McCain says in the recording.
"The first wedge that Donald Trump had that gave him a rise was build a wall, rapist, murderers, etc. And ... if you listen to or watch Hispanic media in the state or the country, you will see that it is all anti-Trump. The Hispanic community is roused and angry in a way that I have never seen," McCain says.
McCain’s campaign spokesperson would not comment on the audio but did point out that he has campaigned hard every time he’s up for re-election.
Trump's words are also being used against Arkansas Sen. John Boozman, who is up for re-election.
He is being challenged by former U.S. Attorney Conner Eldridge, who released an ad that features some statements Trump has made about women and then goes on to call Boozman an "enabler" of harassment since he endorsed the real estate mogul.
"I do think it's fair because when he says 'I'll support Donald Trump' without any other comments, he is enabling and ... implicitly endorsing those comments," Eldridge told ABC News. Boozman did not immediately respond to ABC News' request for comment.
Campbell thinks that these two instances are the first of many. "For Republicans, a long national nightmare still has a long way to go," Campbell told ABC News.
ABC News' Ali Weinberg contributed to this report.