In a final frantic bid to stop Donald Trump, Marco Rubio’s campaign on Friday tried to broker an agreement among Trump’s remaining rivals to embrace a divide-and-conquer strategy to deny Trump the delegates to win the Republican nomination.

Rubio’s campaign urged its supporters to back Ohio Gov. John Kasich in the Buckeye State’s pivotal March 15 primary, in hopes that a Kasich victory there, coupled with a Rubio win in his home state of Florida on the same day, will block Trump from amassing the 1,237 delegates required to sew up the GOP nomination before the party’s convention in Cleveland.

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“If you are a Republican primary voter in Ohio and you want to defeat Donald Trump, your best chance in Ohio is John Kasich,” Alex Conant, Rubio’s communications director, told CNN.

Speaking Friday on ABC’s “Good Morning America,” Rubio suggested that backers of Kasich and Texas Sen. Ted Cruz should throw him their votes in Florida on Tuesday to deny Trump the Sunshine State’s 99 delegates.

“There’s a lot of Kasich and Cruz supporters who realize that neither John Kasich nor Ted Cruz has any chance to win in Florida, and if they don’t want Donald Trump to be our nominee, then voting for John Kasich or Ted Cruz in Florida is a vote for Donald Trump,” he said.

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The idea of a nationwide “tactical voting” agreement has been discussed by party insiders for weeks. Former Massachusetts Gov. Mitt Romney, the GOP’s presidential nominee in 2012, proposed the idea during a speech last week that urged party voters to reject Trump. “I would vote for Marco Rubio in Florida, for John Kasich in Ohio, and for Ted Cruz or whichever one of the other two contenders has the best chance of beating Mr. Trump in a given state,” Romney said.

Rubio’s public embrace of the plan Friday does not mean his rivals will reciprocate.

Rob Nichols, a Kasich spokesman, shrugged off the suggestion Friday, according to the Associated Press. “We were going to win in Ohio, without his help, just as he’s going to lose in Florida without ours,” Nichols said. And while a pro-Cruz group has shifted some of the anti-Rubio advertising it intended to unleash in Florida into other states, the candidate held a rally Friday morning in Orlando.

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Write to Alex Altman at alex_altman@timemagazine.com.