House Speaker Paul D. Ryan said Thursday that he is withholding his support from presumptive Republican presidential nominee Donald Trump, adding to the bizarre and tense conversation that has erupted as the party tries to come to grips with its new standard-bearer.
A few Republicans have said they will back Hillary Clinton rather than cast a ballot for Mr. Trump, and the Libertarian Party is eagerly offering itself to disaffected conservatives as a soft landing spot in November. Still other Republicans say they can’t accept any of the options and are hoping to recruit an independent candidate to challenge the whole lot.
Mr. Ryan said he does want to end up supporting Mr. Trump, though the billionaire businessman will have to convince Republicans that he accepts their philosophy of limited government and must prove he will tone down the bullying and insults that characterized the Trump campaign during the primaries.
“I’m not there right now,” Mr. Ryan told CNN.
He is the latest to struggle with Mr. Trump, who outlasted 16 other major Republican candidates and will claim the party’s presidential nomination at the national convention in July.
Sen. Ben Sasse, Nebraska Republican, wrote an open letter pleading with voters to brainstorm on a viable independent candidate who Republicans could vote for with a clean conscience. He signaled that he isn’t in the running but said there must be someone ready to pick up the pieces.
“These two national political parties are enough of a mess that I believe they will come apart. It might not happen fully in 2016 — and I’ll continue fighting to revive the GOP with ideas — but when people’s needs aren’t being met, they ultimately find other solutions,” Mr. Sasse said in his letter.
Mr. Trump told Fox News that Mr. Sasse was undercutting Republicans and risking the chance that a Democrat will pick the next Supreme Court nominees, firmly tilting the bench to the left for years to come.
“The worst thing that can happen,” Mr. Trump said.
Divisive primaries always leave bad blood, but the divisions in the Republican Party appear to be deeper and ready to linger far longer than in past contests — driven by questions about Mr. Trump’s stances and approach to politicking.
Republican Party officials hope heads will cool by the time the convention opens, and some major figures are already coming on board.
Senate Majority Leader Mitch McConnell of Kentucky said Wednesday that he will support Mr. Trump when he accepts the nomination because it’s too important to stop Democrats from pursuing what would essentially be “a third term of President Obama.”
Rick Perry threw his support behind Mr. Trump, marking a stark turnaround for the former Texas governor who last year called the New York billionaire “a cancer on conservatism.”
“He is not a perfect man,” Mr. Perry told CNN. “But what I do believe is that he loves this country and he will surround himself with capable, experienced people and he will listen to them,” he said.
Mr. Perry tried to salvage his second bid for the White House this year by sounding the alarm about the negative impact Mr. Trump would have on the party. The strategy backfired, and Mr. Perry’s campaign flamed out. He then endorsed Sen. Ted Cruz, a fellow Texas Republican, in January.
Mr. Ryan, though, said it’s up to Mr. Trump to earn his support.
The break is not surprising given Mr. Trump’s campaign message of opposing trade deals and pushing for a crackdown on illegal immigration — both of which are at odds with Mr. Ryan, who has been the biggest Republican advocate for Mr. Obama’s Pacific trade deal and has been a longtime supporter of legalizing illegal immigrants.
“I am not ready to support Speaker Ryan’s agenda,” Mr. Trump said in a statement Thursday evening, firing back at the House speaker. “Perhaps in the future we can work together and come to an agreement about what is best for the American people. They have been treated so badly for so long that it is about time for politicians to put them first!”
Mr. Ryan’s reaction to Mr. Trump is still better than that of Mitt Romney, the 2012 Republican presidential nominee who picked Mr. Ryan as his running mate and who has signaled that he won’t support Mr. Trump. Former Presidents George H.W. Bush and George W. Bush have signaled that they would remain neutral.
The 2008 Republican presidential nominee, Sen. John McCain of Arizona, said he will back Mr. Trump.
Conservative pundits are just as divided. A number of them said they can’t get behind the man they have been trying to stop all year.
It’s not clear, though, whether the soul-searching within the punditry extends down to the roots of rank-and-file Republican voters. Some polls show a sizable number of self-identified Republicans who would back Mrs. Clinton in a head-to-head matchup, while others suggest it’s only about as deep as the divide among Democrats over whether to back Mrs. Clinton.
Anti-Trump conservatives are also coming under intense pressure to acquiesce.
John Andrews, founder of the Western Conservative Summit and former Colorado Senate president, was a staunch supporter of Mr. Cruz but says he now backs Mr. Trump because defeating Mrs. Clinton should be the top priority for all conservatives.
“There is a guaranteed negative scenario if Hillary Clinton is president,” Mr. Andrews said. “There is no guarantee that we will like or dislike different aspects of a Trump presidency.”
He and other Republicans have argued that Mr. Trump’s policies would be subject to influence by House and Senate Republicans as well as other advisers.
“We’re not electing a king, we’re not electing a bishop. We’re electing a chief executive,” Mr. Andrews said. “And a President Trump would be susceptible to tremendous guiding, checking shaping influence upon his policies and his leadership.”