Republicans leaders desperate to stop Donald Trump's presidential bid are prepping a 100-day campaign to deny him the GOP nomination and, if that effort fails, will back an independent candidate in the general election, according to a report Saturday.

William Kristol, the prominent neoconservative editor of The Weekly Standard, sent a memo to allies outlining how backers could get a third party candidate on general election ballots around the country if Trump wins the GOP nomination, the New York Times reported.

The group is eyeing former Texas Gov. Rick Perry and former Sen. Tom Coburn, R-Okla., along with less prominent conservatives for the role, according to the report.

Kristol confirmed the plan on Saturday.

"This is Track Two, just in case," he tweeted, referring to the independent candidate option. "Track One is to stop Trump within GOP, where he's getting only 37% of vote."

Kristol and his allies believe they must act fast. They hope to stop Trump from winning Wisconsin's April 5 primary and execute delegate-by-delegate lobbying based on the argument that Trump's nomination would be disastrous for the Republican Party in the general election and congressional races.

But the reality of a third party challenge to Trump would be to increase Democratic front-runner Hillary Clinton's already rising odds of winning the presidency by splitting the Republican vote.

Coburn, who left the Senate last year to receive treatment for cancer, told the Times that Trump "needs to be stopped." He downplayed but did not rule out the chance he would run against Trump as an independent

"I'm going to support that person," Coburn said, "And I don't expect that person to be me."