Rand Paul has made it a point lately to raise doubts about Hillary Clinton ahead of a probable presidential run for both of them. But the GOP Kentucky senator has gone too far for Fox News host Neil Cavuto.

In an interview with Politico’s Mike Allen this week, Paul wondered if the 67-year-old Clinton will be able to shoulder the burden of a campaign in 2016.

“I think all the polls show if she does run, she’ll win the Democrat nomination,” said Paul, who is 51. “But I don’t think it’s for certain. It’s a very taxing undertaking to go through. It’s a rigorous physical ordeal, I think, to be able to campaign for the presidency.”

Cavuto didn’t like the sound of that.

“Give Rand a hand he just out-Chris-Christied, for shooting himself in the foot,” Cavuto, a host on Fox Business and Fox News, said on-air Tuesday.

Unlike Christie, Paul has generally been in the host’s good graces. Cavuto conducted a softball interview with Paul in June, gamely allowing the Republican to rail against “zealots” and “environmental extremists” in the Obama administration.

In a column published on FoxBusiness.com in July, Cavuto praised Paul (“one crafty Libertarian”) for his overture to Silicon Valley. The New Jersey governor, meanwhile, has occasionally drawn Cavuto’s disdain, most recently for telling a heckler to “sit down and shut up.”

So this criticism toward Paul’s barely veiled ageism was coming from a fan.

“So are you going after Hillary because she’s a Democrat? Or a woman? Or both?” Cavuto said during his Tuesday monologue. “Either way, you’ve done more damage with that condescending swipe than Chris Christie could do shaking a thousand ice cream cones in critics’ faces.”

He continued, “By all means, go after Hillary Clinton on the issues that matter not the silly ones that don’t. You’d hate it if it were done to you. So don’t pull this nonsense with her. Because she’s no more Methuselah than you are Mensa material.”