Three prominent conservatives have issued an invitation to several other top leaders on the right to meet in Washington, D.C. on Thursday to discuss ways to halt Donald Trump's march to the nomination and failing that, talk about the possibility of forming a third party with a "true" conservative as a candidate.

Politico:

The organizers of the meeting include Bill Wichterman, who was President George W. Bush’s liaison to the conservative movement; Bob Fischer, a South Dakota businessman and longtime conservative convener; and Erick Erickson, the outspoken Trump opponent and conservative activist who founded RedState.com.

"Please join other conservative leaders to strategize how to defeat Donald Trump for the Republican nomination,” the three wrote in an invitation obtained by POLITICO that recently went out to conservative leaders, "and if he is the Republican nominee for president, to offer a true conservative candidate in the general election."

The meeting is scheduled for Thursday, two days after winner-take-all Florida and Ohio vote in what many Republican operatives believe will determine whether Trump is on an unstoppable march to the nomination or is likely to stall out short of the 1,237 delegates he needs.

One person involved in the gathering described it as in the “embryonic” stages.“ It’s not like there’s a royal grand plan that’s going to be unfurled," this person said. "People aren’t giving up on the Republican Party yet."

Still, Wichterman, Fischer, and Erickson represent three boldface names to host such a gathering. All three have deep ties to the social conservative movement, which Ted Cruz has tried to unite behind his candidacy.

Wichterman, in addition to his top job for Bush, served as a senior adviser to Senate Majority Leader Bill Frist. He now works for Covington, a law firm in Washington, D.C.

Fischer, in 2012, helped bring together a group of more than 200 conservatives from across the country to unite around Rick Santorum’s candidacy. An event in Houston he put together raised $1.8 million in a day.

And Erickson, who has sparred publicly with Trump for months online and on his radio show, has previously said, “I will not be voting for Donald Trump at all. Ever.”

If they are serious about a third party effort, they needed to start yesterday.  Filing deadlines for some states are just days away, and it's unlikely that the signatures necessary to reserve space on some state ballots for another party can be gathered in so short a time.

So their efforts will be directed at trying to deny Trump the nomination at the convention.  Even if Trump fails to win the 1,237 delegates necessary for the nomination, he will likely be so far ahead of Ted Cruz and so close to the magic number that denying him the nomination will blow up the party and lead to certain defeat in November.

For those who believe that Trump must be stopped at all costs, the prospect of blowing up the party seems an acceptable risk.  But most Republicans – even if they can't stand Trump – won't go so far as to destroy the party to stop him.  For good or ill, it is likely that Donald Trump will be the nominee, and no amount of manuevering by "true" conservatives or the establishment will be able to alter that fact.