How Ted Cruz won the Wisconsin GOP primary, in 60 seconds (Peter Stevenson/The Washington Post)

After his most convincing victory yet over Donald Trump in Wisconsin, Ted Cruz sought on Wednesday to shed his reputation as a divisive bomb-thrower and position himself as the candidate who can bring the Republican Party together.

But it wasn’t clear whether it was working. In Washington and across the country, many mainstream Republicans who despise Trump — including many supporters of former candidate Marco Rubio — are still declining to support the senator from Texas, whose antagonism toward GOP leaders has been the centerpiece of his political rise.

The lukewarm reception highlighted the difficulty Cruz faces in recasting himself as a bridge builder after years of bridge burning. Many top Republicans remain strongly opposed to both Cruz and Trump and hold out hope that long-shot candidate John Kasich, or perhaps another Republican not in the race, can somehow clinch the nomination.

“I think stopping Donald Trump has got to be the number one goal, and to rally around Ted Cruz in these future primaries I think is important,” said billionaire GOP donor Frank VanderSloot, who backed Rubio. “But neither I nor very many of the people I know are enamored with Ted Cruz, and I think that everyone is hoping it is a brokered convention where we can have a third choice.”

Cruz’s attempts to broaden his appeal beyond evangelical Christians and tea-party activists will be crucial in the upcoming slate of Northeastern primaries, beginning on April 19 in New York. A Monmouth University poll released Wednesday showed Cruz trailing Trump and Kasich in the Empire State.

Addressing reporters at a Dominican-Chinese restaurant in the Bronx, Cruz underscored the unity message he delivered in Milwaukee after his primary win.

“We saw Republicans come together and unite, stand united, and really that’s what this election is all about. It is about unity. If we come together, we’re going to win. If we remain divided, we will not, and I could not be more encouraged,” he said.

In recent weeks, Cruz has struck a more inclusive tone. He reached a new register in his Milwaukee victory speech by seeking to draw a contrast with Trump’s antagonism.

“Wisconsin has lit a candle guiding the way forward. Tonight, we once again have hope for our future. Tonight is about unity, and tonight is about hope,” he said.

But the words didn’t move support on Capitol Hill on Wednesday.

“I have my own town-hall meeting, and I quite frankly didn’t watch any of it,” said Rep. Jason Chaffetz (R-Utah), a former Rubio backer who said he has no plans to make another endorsement.

While Cruz has won the support of five former candidates, Rubio has held out. So have many of the donors and elected officials who backed him.

Tracking the race to the Republican nomination

Cruz has tapped former U.S. senator Phil Gramm (Tex.) to head up his outreach on Capitol Hill. Since his 2013 arrival in the Senate, Cruz has ruffled feathers on both sides of the Capitol, openly plotting against Republican leadership on a series of issues and helping force a government shutdown in 2013.

Gramm said racking up endorsements has not been his main goal because they don’t mean as much this late in the race. Instead, his target has been opening lines of communication and working toward crafting a platform that Republicans up and down the ballot can run on this fall.

“My message has not been what we want from you, but what we want to do with you,” said Gramm, who said he has spoken with House and Senate Republican leaders.

Sen. Mike Lee (R-Utah), one of just two senators backing Cruz, is also trying to cultivate relationships on the Hill. He is making a concerted effort to woo Rubio for an endorsement, for example.

But in a chamber where Cruz has irked his colleagues, the firebrand Texan is proving to be a hard sell.

Take Sen. Cory Gardner (R-Colo.), a freshman conservative whose first choice for president was Rubio and his more optimistic tone.

As the Colorado Republican Party finalizes delegate selections this weekend, Gardner’s support might be a huge boost to Cruz, but no such endorsement is coming.

“Any nominee is going to have to earn my support, just like they’ll have to earn the support of the delegates this weekend in Colorado,” he said.

Lee played down Cruz’s lack of support in the Senate, arguing that those who supported candidates who have dropped out may be “gun shy.”

“They have swung and missed once or in some cases multiple times, and they are not necessarily anxious to jump on board,” said Lee.

Sen. David Perdue (R-Ga.) has spoken directly with Trump and with Cruz but said he has no plans to endorse anytime soon and is trying to get the presidential candidates to focus their campaigns on the national debt. Sen. Bill Cassidy (R-La.) said he has not heard from the remaining candidates or their surrogates and suggested that they shouldn’t bother trying to win endorsements from Washington.

“Let’s face it, Senate endorsements haven’t had much sway,” Cassidy said, an indirect reference to the strong support that Rubio and former Florida governor Jeb Bush had in the chamber.

In Wisconsin, Cruz showed an ability to expand his support beyond his natural base. Exit poll data showed that he won a plurality of non-born-again or evangelical Christians, for example.

With April 26 primaries in Connecticut, Delaware, Maryland, Pennsylvania and Rhode Island — states where Republicans tend to be more moderate than Cruz — he will face new tests soon.

New York could be especially difficult for Cruz, who has clashed with officials there.

“I’m not going to make any endorsement before the primary,” said Rep. Peter T. King (R-N.Y.), a frequent Cruz foe. “But I have high regard for Kasich, no regard for Cruz, and Trump is a work in progress.”

Tim Pawlenty, the former Minnesota governor and 2012 presidential candidate, wrote in an email that Cruz’s win in Wisconsin “gives him momentum and an increased likelihood of a contested convention at which he would have some advantages.”

But Pawlenty, who was a Rubio supporter, added that he has “not yet decided what I might do next in this race.”

Minnesota media mogul Stanley Hubbard, a top GOP donor, said he gave to many candidates, including Cruz, and hit his maximum level of candidate giving allowed under the law. Although he is permitted to give unlimited sums to super PACs — such as those backing Cruz — he said he will wait until the nomination process is done before cutting any more checks.

“I was never a big supporter of Mr. Cruz, but he’s been a gentleman,” Hubbard said.

Katie Zezima in New York and David Weigel in Washington contributed to this report.