Charles Krauthammer predicted tonight that Donald Trump’s threats of mounting a third-party bid are just a bluff. Commenting on the 2016 front-runner once again saying he might abandon his pledge to run as a Republican, Krauthammer said that in Trump’s eyes, the pledge “isn’t worth the paper it’s written on.”

Appearing on Wednesday’s Special Report on Fox News, Krauthammer explained why he doesn’t think Trump will end up running as anything other than a Republican:

I suspect that his ego will not — that would restrain him from running as a third party, assuming he doesn’t win the nomination. Because it’s going to be a lot harder than he thinks. And there will be a bar, sort of an invisible bar. And I think that’s going to be the Ross Perot number of 19 percent. I don’t think he would come anywhere near that in a general election. And that will be his mark on history and I don’t think he likes to be seen as a loser. The Republican nomination is his shot and I think that’s what he wants to go for.