Donald Trump argued Monday that Sen. Marco Rubio would be a bad choice for president because he'd have to sweat out meetings with world leaders like Russian President Vladimir Putin.

And Trump meant literally that Rubio would be glistening with perspiration in those meetings, based on his debate performances so far.

"He was soaking wet," Trump said of Rubio in the last debate. "He was wet, I said what the hell's going on over here. I thought he just came out of a swimming pool."

"When we get in with Putin, we need people that don't sweat, let me tell you," Trump said to applause at a rally in Greenville, S.C. "Gotta have people that don't sweat."

"Can you imagine Putin sitting there, waiting for the meeting, and this guy walks in and he's like a wreck," he added. "You gotta have Trump walk into that meeting, folks. We'll do very nicely."

Trump said it's time to have better relations with Russia anyway, and said he doesn't understand critics who say Trump shouldn't be advocating working with Russia.

"Donald Trump wants to work with Russia to get rid of ISIS?" he said, mimicking his critics. "Yeah, sort of."

Trump also dismissed calls for him to disavow Putin for calling him a genius.

"First of all, I say this," he said. "Guy calls you a genius, you're not going to disavow. Only a stupid person would disavow. No genius would disavow being called a genius."