DETROIT — A growing sense of crisis enveloped the Republican Party Wednesday after Donald Trump’s strong Super Tuesday performance, with 2012 Republican nominee Mitt Romney preparing to call for a united front against Trump and Massachusetts Governor Charlie Baker saying that he would not support him in the general election.
From congressional corridors to State House hallways, party leaders fretted about Trump’s candidacy and the damage his divisive rhetoric about immigrants and Muslims has inflicted on the party, but remain seemingly powerless to slow his momentum.
In a sign of growing desperation among GOP elites, Romney planned to step off the sidelines more aggressively and deliver a speech in Utah Thursday about the 2016 nomination battle. Close advisers said Romney was not planning to enter the race himself or to endorse anyone, but instead would seek to use his leverage as an elder statesman to unify the party.
Meanwhile, Baker on Wednesday became one of the most prominent sitting officeholders outside of Washington to say he would not support Trump if he is on the ballot in November. But he said he was not convinced Trump would wind up as the GOP’s nominee.
And on Capitol Hill — where at least one senator, Ben Sasse of Nebraska, has talked about starting a new political party if Trump is the GOP nominee — senators were aghast at the growing Trump phenomenon and the TV reality star’s rebranding of the GOP.
“I’ve watched him demean races, religions, handicapped people. This is not my party. This is not what I’ve believed in for the last 50 years,” said Senator James Risch, an Idaho Republican who endorses Marco Rubio. But, he said, “people are so angry they are willing to blow the thing up and overlook everything Trump’s done.”
The Republican Party establishment, splintered for much of the nominating contest among several different candidates, has struggled with how to deal with Trump. First they dismissed him. Then they underestimated him. Now, they’re overwhelmed by him.
Trump has won 10 of the first 15 nominating contests. He holds a comfortable lead in delegates, but he’s only one-fourth of the way toward the 1,237 needed to secure the nomination.
One of the last hopes for those who want to deny Trump the nomination is to prevent him from getting a majority. That would lead to a contested convention, releasing delegates pledged to him and potentially allowing another candidate to win. But there are enormous risks for the party’s political establishment if the effort to derail a Trump candidacy alienates voters across the country.
“If someone rolls into that convention with a majority of votes and majority of delegates and the establishment — either perceived or real — tries to take the nomination from the leading vote-getter, then there’s going to be a political jihad like you’ve never seen,” said Hogan Gidley, a Republican consultant. “That’s going to be an absolute disaster, on many levels.”
“The establishment wouldn’t be rejecting Donald Trump,” he added. “They’d be rejecting the will of the voters.”
Trump appeared to lay low Wednesday after his impressive night, but he was posting messages on Twitter. “Why can’t the leaders of the Republican Party see that I am bringing in new voters by the millions — we are creating a larger, stronger party!’’ he wrote.
Trump in his victory speech Tuesday appeared to recognize the challenges he faces after his campaign of divisiveness. He called himself a unifier. He joked that he was learning how to be diplomatic. He has boasted about endorsements of several prominent GOP politicians, including conservative Senator Jeff Sessions of Alabama and moderate New Jersey Governor Chris Christie.
Boycotting Trump or trying to derail him at the convention could lead to the splitting of the party, some warned.
“Look I’m going to support anybody that comes through the Republican process,” said Senator David Perdue Jr. a Georgia Republican. “If people don’t like the Republican process, we need to change the process.”
With no coherent party effort to bring him down — and after months of displaying a meek unwillingness to attack him — the scattershot strategy so far has the feel of a potluck supper: Everyone brings something, with the hopes that at least one dish is a success.
Rubio criticized Trump for his support of Planned Parenthood, while Romney has ridiculed Trump for not releasing his tax returns. The conservative Club for Growth is taking out ads in Florida citing bankruptcies by companies owned by Trump. Two anti-Trump super PACs are airing ads that target Trump’s real estate program, Trump University, currently the subject of a lawsuit filed by former students accusing it of fraud. One ad features people who claim they were duped by Trump’s program, while another calls it a “scam.”
“The Trump brand is going to poison the image of Republicans and conservatives for generations to come,” said Rick Wilson, a Republican strategist in Florida who is working with one of the Super PACs backing Rubio. “We’re going to, as a political party, end up selling our souls to a narcissistic lunatic. We will end up sitting around campfires in the ruins of the party telling our grandchildren what it was like in the age of Reagan and Bush.”
Senate Republicans on Wednesday appeared divided into two camps: those who disavow the Trump brand, saying it does not represent the Republican Party they know, and those — especially senators running for reelection like Johnny Isakson of Georgia and the normally verbose John McCain of Arizona — and those who are wary of coming down against a presumptive nominee who has drawn a flood of voter support from all corners of the country.
Senator Cory Gardner, a Colorado Republican and Rubio supporter, urged fellow Republicans to take sides on Trump.
“Look at the damage he’s already done. He says he’s a person of unity. That’s like putting two negatives of a magnet together,” Gardner said.
Some Republicans in the key swing states of Ohio and Florida have vowed to shun Trump if he wins the nomination, embracing the Twitter hashtag #NeverTrump.
“Donald Trump will ensure that the state of Ohio becomes blue for the next four to eight years,” said Clarence Mingo, Franklin County auditor in the Columbus area. “This could set us back decades, injuring the reputation and the character of our party nationally.”
Romney, who has grown increasingly alarmed by Trump’s strength, is planning to speak at the University of Utah at 11:30 a.m., before the Republican candidates gather in Michigan for another debate.
A person close to Romney said, “this is not an endorsement or announcement of candidacy.”
Romney has grown more pointed in his criticism of the front-runner for the nomination that Romney himself captured just four years ago. Last week, he raised questions about Trump’s taxes, calling on him to release tax returns soon and suggesting they contained a “bombshell.”
“Mitt is discouraged by the direction the party is going in,” said Eric Fehrnstrom, one of his longtime advisers. “What he looks for in a candidate is someone with even temperament who has the capability and skills to guide the country, particularly as it relates to the country’s foreign policy.”
Romney has yet to endorse any candidate, but has had glowing words for Rubio.
While Trump endorsed Romney’s 2012 bid, he has repeatedly criticized Romney for losing the race.
Matt Viser can be reached at firstname.lastname@example.org. Joshua Miller of the Globe staff contributed to this report.