Former GOP presidential hopeful George Pataki said Monday that Republicans could nominate someone at their convention this summer who didn't run in the 2016 presidential primary.
"I don't think it has to be someone who was a candidate," Pataki, who ended his White House campaign in December, said during an appearance on MSNBC's "Morning Joe."
GOP leaders have for weeks pushed back on the suggestion that someone other than the three remaining candidates could emerge as the nominee at a contested convention in July.
Donald TrumpDonald TrumpRomney blasts end of filibuster, expansion of SCOTUS McConnell, GOP slam Biden's executive order on SCOTUS US raises concerns about Iran's seriousness in nuclear talks MORE, the front-runner, has argued he should win the nomination if he enters the convention with a plurality of support but is short of the 1,237 delegates needed to secure the nomination outright. 
Sen. Ted CruzRafael (Ted) Edward CruzGOP lawmakers block Biden assistance to Palestinians Cruz on Boehner: 'I wear with pride his drunken, bloviated scorn' The Hill's Morning Report - Biden: Let's make a deal on infrastructure, taxes MORE (Texas), who is running closest to Trump in the delegate race, and Ohio Gov. John Kasich have sought to keep the businessman below that target, which would force a contested convention and multiple rounds of voting.
"I think, if it comes down to the convention where Trump doesn't have a majority and after the first ballot the delegates can say, 'Who would be the best president? Who can unite the party and win?' And if that person is available, I think we should nominate that person," Pataki said Monday.
"I don't care if they ran for president or not," he added.
The former New York governor endorsed Kasich last week and is slated to appear on the campaign trail with him.  
Pataki predicted that while Trump is "going to win" the New York primary on Tuesday, the billionaire may fall below the 50 percent threshold in enough districts to allow Kasich to pick up some delegates.
"I think the key is to stop Donald Trump, to not let him become the nominee before the convention. Then at the convention, the delegates are free to choose whoever they want," Pataki said.
"And I think the delegates are going to take a look and say, 'Who can win in November?' I think they're going to be pragmatic and want to win," Pataki added.
"I think John Kasich would win in November, and I think that Ted Cruz could win. I think the one certainty is that Donald Trump goes down in flames."