Suddenly, Republicans are confronting a reality that seemed fantastically implausible not long ago: Donald Trump as their all-but-official presidential nominee.
The response Wednesday in some quarters was a combination of denial and resistance that was unlike anything seen in recent history.
Republican leaders, including some who sparred with Trump, pleaded for unity. Prominent GOP lawmakers announced their support. So did some tea party activists.
But many Trump detractors were unmoved. Talk of finding a third-party alternative continued unabated. Big-money donors, including the Koch brothers and casino mogul Sheldon Adelson, were notably silent, as was Mitt Romney, Republicans' last presidential nominee and a fierce Trump critic.
The overwhelming sentiment — at least within the party establishment, which Trump vilified but now must work alongside to win in November — seemed to be resignation mixed with a determination to make the best of things.
"The final stage is acceptance, which I think a lot of people will get to," said Josh Holmes, a Republican strategist unaligned with any candidate. But, he added, "I don't think we're going to see a seismic shift in people supporting Trump."
The prospect of a primary fight extending all the way to a contested July convention instantly vanished Tuesday night after Trump roared to victory in Indiana and his closest contestant, Texas Sen. Ted Cruz, unexpectedly stepped aside. Trump's sole remaining rival, Ohio Gov. John Kasich, followed suit on Wednesday, becoming the last to abandon a field that once comprised 17 hopefuls — including many of the party's most acclaimed leaders. Pointedly, Kasich made no mention of the presumptive nominee.
Trump must still collect the 1,237 delegates he needs to officially clinch the nomination, which will take him until the end of the primary season on June 7, when California and four other states vote.
His critics weren't yielding, despite the lack of any Republican opponent.
Ample time remains for Trump to "disqualify" himself, said Katie Packer, a GOP consultant and head of Our Principles PAC, which has spent millions on advertisements across the country attacking Trump.
"We continue to give voice to the belief of so many Republicans that Trump is not a conservative, does not represent the values of the Republican Party, cannot beat Hillary Clinton, and is simply unfit to be president of the United States," she said in a statement that defied party efforts to rally behind the nominee-in-waiting.
Trump will enter the general election, presumably against Clinton, as a decided underdog.
There are a few Democratic-leaning states he might make more competitive, such as Pennsylvania, with its large population of disaffected working-class whites. But there are others that have been reliably Republican, like Arizona and Georgia, that could come into play if Latinos and other minorities, antagonized by Trump's insults, turn out in high numbers.
In Nevada, a major battleground in the last few elections, the state Democratic Party sent a taunting letter Wednesday urging Trump — "Dear Dangerous Donald" — to campaign there, figuring it would hurt his candidacy and other Republicans as well.
"General election," wrote Nevada Democratic Party Chairwoman Roberta Lange, "here we go!"
Trump spent much of Wednesday looking ahead to the November election, including how he might finance a campaign costing up to $1 billion.
"Do I want to sell a couple of buildings and self-fund?" the Manhattan real estate developer mused on MSNBC. "I don't know that I want to do that necessarily."
Later, in an interview with the Wall Street Journal, Trump said he would not self-fund his general election campaign but rather create a "world-class finance organization."
The move carries some risk. After spending months accusing rivals of trading government favors for donations and claiming, inaccurately, that he alone was paying for his candidacy, Trump faces the danger of undermining his outsider image by accepting big campaign contributions. He has raised more than $12 million, mostly in small sums.
Trump also said he was searching for a seasoned politician with expertise in navigating Congress to be his vice presidential running mate. "I have the business — let's call it talents," Trump said on MSNBC. "And I think I'll probably go the political route."
First, Trump must pull his party together, which will not be easy.
Some, more or less grudgingly, said they were coming around to the idea of supporting the businessman and reality TV star, even if he was not their first, second or third choice.
"Donald Trump has struck a chord with a lot of people," said Jonathan Barnett, a member of the Republican National Committee from Arkansas and a longtime supporter of the state's former governor, Mike Huckabee, who quit the presidential race in February. "Even though they may not care for him and may not like him personally, and he may not represent their values ... they want to give him a chance to try to work these issues out."
But others insisted, in the words of Rory Cooper, a spokesman for the Never Trump political action committee, that "never means never."
In a highly unusual snub, the party's last two presidents, George H.W. Bush and George W. Bush, have both ruled out a Trump endorsement, the Texas Tribune reported Wednesday. Trump was relentless in mocking Jeb Bush, the former Florida governor, during his unsuccessful attempt to follow his father and brother into the White House.
Social media were filled Wednesday with images of voters burning their Republican registration cards, professing their abandonment of the party or vowing to cross party lines to support Clinton.
Among them was Mark Salter, a former top aide and confidant to Arizona Sen. John McCain, the 2008 Republican nominee.
"The GOP is going to nominate for President a guy who reads the National Enquirer and thinks it's on the level," Salter wrote on Twitter, referring to Trump's embrace of an unsubstantiated report that linked Cruz's father to President Kennedy's assassination.
"I'm with her," Salter said of Clinton.
The resistance to Trump extends beyond party elites.
Even as he rolled to victory in Indiana, more than 4 in 10 of those who voted in Tuesday's Republican primary said they were "scared" or "concerned" about the prospect of a Trump presidency, a finding consistent with previous exit polls.
Curt Anderson, who worked for another of the unsuccessful 2016 GOP candidates, former Louisiana Gov. Bobby Jindal, said some "in the professional political class" will never support Trump.
"The question is ... will it just be a couple hundred of these folks?" Anderson said. "Or will it be millions of normally reliable Republican voters who refuse to come over to Trump?"
Barabak reported from San Francisco and Mascaro from Washington. Times staff writers Melanie Mason in Indianapolis and Michael Finnegan and Seema Mehta in Los Angeles contributed to this report.
6:21 p.m.: This story has been revised throughout for additional details and for clarity.