It’s hard to tell if conservative pundit William Kristol was being serious or just wanted to mess with presumptive Republican presidential nominee Donald Trump when he tweeted a promise over the weekend that a conservative third-party alternative to the billionaire would soon declare interest in the presidency.

“Just a heads up over this holiday weekend: There will be an independent candidate--an impressive one, with a strong team and a real chance,” he wrote.

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It was a strange thing for Kristol, who edits the Weekly Standard, to just toss off in the middle of a holiday weekend. The move to draft a high-status conservative to challenge Trump under the banner of a third party has been around for some time and has so far been thoroughly unsuccessful. Hoped-for candidacies of retired Marine Corps general James Mattis, former GOP presidential nominee Mitt Romney or vice presidential nominee Paul Ryan have all fizzled out.

Likewise, the assertion that a third-party candidate would, at this point, have “a strong team and a real chance” seems optimistic. It’s late in the game to launch a presidential bid, and unless the candidate Kristol has in mind already has Trump-like name recognition, the effort to get his or her name on ballots across the 50 states and to persuade at least a plurality of the electorate to deliver their votes would be daunting.

Similarly, developing a “strong team” would be a major challenge this late in the game. Though to be fair, there are a lot of experienced Republican operatives within the #NeverTrump movement who would probably jump at the chance to join a credible opposition campaign.

Kristol’s promise was immediately leapt upon by Trump supporters. Calling it a “betrayal of this country," Breitbart.com writer David Horowitz huffed, “The Kristol attack on the Republican Party and its presumptive candidate Donald Trump is an attack on all Americans and needs to be seen in that light.”

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Trump himself took to Twitter, as is his wont, to blast the conservative pundit as a “loser,” “dummy,” "lightweight” and more. In a series of tweets that suggested a certain degree of nervousness, he warned that if the erstwhile Republican establishment indeed launches or supports a third-party bid, the result would be to hand the presidency to Hillary Clinton.

“Say Goodbye to the Supreme Court,” Trump warned.

And there’s little doubt that on that score at least, Trump has it right. A more traditional Republican candidate running as an independent would give #NeverTrump Republicans who cannot abide Hillary Clinton an alternative to the two major party candidates.