Some Republican leaders kept straining Thursday to come up with a way to stop Donald Trump's likely ascent to the GOP presidential nomination while others seem headed for grudging acceptance.

In this March 14, 2016, photo, Republican presidential candidate Donald Trump speaks at a campaign event in Tampa, Fla. (AP Photo/Gerald Herbert)

With at least this week's additional states in his win column, Trump is now the only candidate with a path to clinching the Republican nomination before the party's convention in July. But he still must do better in upcoming contests to get the necessary 1,237 delegates, leaving some opponents with a sliver of hope he can  be stopped.

"I still think it's a very realistic chance that nobody's going to have a majority of the delegates," said Henry Barbour, a senior Republican National Committee member who worked on Marco Rubio's delegate strategy until the Florida senator exited the race Tuesday.

There were incremental steps by some Republicans to rally around Ted Cruz, the only candidate in the race with even a long-shot chance of overtaking Trump in the delegate count.

South Carolina Sen. Lindsey Graham, who has been sharply critical of Cruz in the past, said he would help the Texas senator raise money. Graham said that while Ohio Gov. John Kasich is his preferred candidate, he didn't believe Kasich has a path to stopping Trump, saying that "is most important to me."

A group of conservatives huddled in Washington Thursday morning to discuss ways to block the businessman. Organizer Erick Erickson said in a statement that the group was calling for a "unity ticket that unites the Republican Party" and was also open to unspecified "other avenues" for stopping Trump from becoming the nominee.

While the statement did not mention specific candidates, one participant said the majority of people in the meeting wanted to name Cruz as a suggested nominee but were worried about doing so because of the effect if might have on Kasich. The person insisted on anonymity because they were not authorized to discuss the private meeting publicly.

The three best-financed efforts to stop Trump --  American Future Fund, Our Principles and Club for Growth have no Trump attack ads planned for Arizona -- a crucial winner-take-all contest in six days -- or in any states beyond. Club for Growth did buy about $200,000 in ads in Utah, which also votes next week.

Former House Speaker John Boehner floated his successor, Paul Ryan, as the nominee in the event of a convention fight. But Ryan quickly took himself out of the mix, saying through a spokeswoman that he would "not accept a nomination and believes our nominee should be someone who ran this year."

Meanwhile, Democratic front-runner Hillary Clinton set her sights on a November showdown with Trump. Her victories in four primary contests Tuesday was a harsh blow to rival Bernie Sanders, giving Clinton what her campaign manager described as an "insurmountable lead" in the delegate count.

"We are confident that for the first time in our nation's history, the Democratic Party will nominate a woman as their presidential nominee," Robby Mook wrote in a memo to supporters.

Clinton has at least 1,599 delegates to Sanders' 844. It takes 2,383 to win the Democratic nomination.

Trump urged Republicans to view the party's nominating contest with the same sense of clarity. He said some of the same Republican senators who publicly criticize him have called privately to say they want to "become involved" in his campaign eventually.

Trump also effectively killed the GOP debate scheduled for Monday in Utah, saying "we've had enough debates." After Ohio Gov. John Kasich said he wouldn't debate without Trump on stage, host Fox News scrapped the event.

Trump has won 47 percent of the Republican delegates awarded so far, according to the Associated Press delegate count. He needs to win 54 percent of the remaining delegates to clinch the nomination by the time the primary season ends on June 7.

Just a handful of states will vote between now and mid-April, a reprieve for opponents.

"We've got four weeks to identify what the most effective path is," said Tim Miller, a former Jeb Bush aide who now works for an anti-Trump super PAC.

Former Senate Majority Leader Trent Lott, who is supporting Kasich, said there were "calls going back and forth between the Kasich-Rubio campaign" about the possibility of a joint ticket, though he said those conversations were preliminary.

Any scenarios that end with blocking Trump could leave the party in chaos. But some Republicans suggested that given the party's current state, the chaos couldn't get much worse.

"The divisions are already there," said John Jordan, a California-based donor who was leading a pro-Rubio super PAC. "There's already open warfare on TV. A couple thousand people in a food fight in Cleveland pales in comparison."

(Copyright 2016 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)


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