Republican presidential candidates Ted Cruz Rafael (Ted) Edward CruzSenate Republicans face tough decision on replacing Ginsburg Cruz: Trump should nominate a Supreme Court justice next week Renewed focus on Trump's Supreme Court list after Ginsburg's death MORE and John Kasich anounced Sunday they would work together as part of a joint effort to prevent party front-runner Donald Trump Donald John TrumpObama calls on Senate not to fill Ginsburg's vacancy until after election Planned Parenthood: 'The fate of our rights' depends on Ginsburg replacement Progressive group to spend M in ad campaign on Supreme Court vacancy MORE from winning the Republican presidential nomination.

The Cruz-Kasich joint strategy is intended to keep Trump from winning the 1,237 delegates he needs to clinch the nomination. That would lead to a contested Republican National Convention in Cleveland this July, a scenario in which Cruz and Kasich both think they could end up on top.

As part of the strategy, Kasich will clear a path for Cruz in next week’s Indiana primary, while the Texas senator will back down in two other states.

The two campaigns released statements minutes apart late Sunday night, telegraphing their strategies and calling on their supporters to follow suit.

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“Donald Trump doesn’t have the support of a majority of Republicans — not even close, but he currently does have almost half the delegates because he’s benefited from the existing primary system,” Kasich chief strategist John Weaver said in a statement.

“Our goal is to have an open convention in Cleveland, where we are confident a candidate capable of uniting the Party and winning in November will emerge as the nominee.”

Cruz campaign manager Jeff Roe echoed Weaver’s criticism of Trump and laid out his own strategy to pull out of Oregon and New Mexico.

“We would hope that allies of both campaigns would follow our lead,” he said.

Trump's campaign ripped the move by his rivals.

"It is sad that two grown politicians have to collude against one person who has only been a politician for ten months in order to try and stop that person from getting the Republican nomination," Trump said in a statement early Monday.

"Collusion is often illegal in many other industries and yet these two Washington insiders have had to revert to collusion in order to stay alive," he added.

Trump won a huge victory last week in New York's primary and is expected to have another big night Tuesday when Pennsylvania and four East Coast states vote.

In Indiana, however, Trump holds just a single-digit lead over Cruz in most recent polls. There hasn’t been recent polling in either Oregon or New Mexico.

Both Kasich and Cruz are mathematically eliminated from securing the nomination on the first ballot, while Trump would have to win about 60 percent of the remaining delegates in order to lock up the required 1,237 delegates.

"Never Trump" groups had been calling on Kasich to stand down in Indiana in order to clear a path for Cruz, but he had not shown signs of backing down until now. His campaign claimed an inside-baseball victory in the state weeks before the primary, arguing it had secured the loyalties of the plurality of delegates, who could defect to Kasich in a contested convention.

Cruz has repeatedly framed a vote for Kasich, who sits hundreds of delegates behind him, as a vote in favor of Trump. And Kasich has regularly shot back by arguing that he is the only candidate that polls show beating Democratic front-runner Hillary Clinton Hillary Diane Rodham ClintonWhat Senate Republicans have said about election-year Supreme Court vacancies Bipartisan praise pours in after Ginsburg's death Trump carries on with rally, unaware of Ginsburg's death MORE in the general election.

One anti-Trump group formed by allies of former House Majority Leader Eric Cantor Eric Ivan CantorThe Hill's Campaign Report: Florida hangs in the balance Eric Cantor teams up with former rival Dave Brat in supporting GOP candidate in former district Bottom line MORE (R-Va.) lauded the move in a statement.

"Whether you support Ted Cruz or John Kasich, a second ballot at the Convention is imperative to stopping Donald Trump," #NeverTrump senior adviser Rory Cooper said in a statement.

"We're happy to see the Kasich and Cruz campaigns strategically using their resources to deny Donald Trump delegates where they are in the strongest position to do so."

This report was updated on April 25 at 9:17 a.m.