Presumptive Republican nominee Donald Trump is blasting Bill Kristol, editor at The Weekly Standard.

Bill Kristol has been wrong for 2yrs-an embarrassed loser, but if the GOP can't control their own, then they are not a party. Be tough, R's! — Donald J. Trump (@realDonaldTrump) May 29, 2016

The Republican Party has to be smart & strong if it wants to win in November. Can't allow lightweights to set up a spoiler Indie candidate! — Donald J. Trump (@realDonaldTrump) May 29, 2016

If dummy Bill Kristol actually does get a spoiler to run as an Independent, say good bye to the Supreme Court! — Donald J. Trump (@realDonaldTrump) May 29, 2016

Trump’s tweets come after Kristol posted on Twitter, “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.”

For weeks, the conservative opinion magazine’s Kristol spoke about an independent presidential candidate who could challenge Trump.

“Possible names that have been floated include 2012 Republican candidate Mitt Romney, Ohio Gov. John Kasich, Nebraska Sen. Ben Sasse and even billionaire businessman Mark Cuban,” Business Insider reports. “Kristol was one of 22 prominent conservative thinkers who signed an anti-Trump manifesto in January, when Trump was narrowly leading a wide-open Republican primary with 12 candidates.”