REUTERS/Lucas Jackson
Donald Trump gestures during a news conference at Trump Tower in Manhattan, New York, U.S., May 31, 2016.
Kristol tweeted Sunday that there would be an "independent candidate - an impressive one, with a strong team and a real chance," prompting Trump to tweet in response, calling Kristol a "dummy." Kristol responded that he hoped Trump's "nervousness about an independent candidacy doesn't affect his composure."
Trump, the presumptive Republican nominee for president, continued his attacks against Kristol on Tuesday, saying he couldn't win as an independent.
"For the most part, you can't even get on Texas and various other states now, it's too late," Trump said, referring to state ballots. "... So here's what happens. What happens is ... you will not have Supreme Court justices."
Trump later said that an independent candidate could lose the general election for Republicans, which would put Supreme Court justice nominations in the hands of Democrats.
He explained:
If they do an indy, assuming it's decent, which I don't think anybody with a reputation would do it because they'd look like fools. But what you're going to do is you lose the election for the Republicans, and therefore you lose the Supreme Court. Therefore, you will have a group of people put on the Supreme Court where this country will never, ever recover, it will never, ever be the same.
Trump also called Kristol a "loser" and railed against his "failing" magazine.
Kristol's the one who, he's the last one. Don't forget, he said, 'Trump will never run.' The guy's not a smart person. He said, 'Donald Trump will never run.' Remember? Do you remember? I actually blame you, why do you put this guy on television? I see him on the different shows. He's got no credibility. Said I won't run, if I run I won't do well. ... He looks like such a fool.
He later continued: "Bill Kristol's a loser. His magazine is failing. ... I don't think it even survives. He's getting some free publicity."
It's unclear whether Kristol is actually planning to mount some kind of bid against Trump. A source who's part of the effort to find an independent candidate to run against Trump and the presumptive Democratic nominee, Hillary Clinton, told CBS News that there won't be an announcement about a potential challenger for a couple of weeks.