Trump needled Paul in a series of tweets:

Lightweight Senator @RandPaul should focus on trying to get elected in Kentucky--- a great state which is embarrassed by him.

I truly understood the appeal of Ron Paul, but his son, @RandPaul, didn't get the right gene.

Too many people on stage for debate. @RandPaul at 11th, with 2% in @RealClearNews, shouldn't be allowed to participate.

Trump's shots came hours after Paul joked about the GOP frontrunner in an interview with Politico.

"I think I was a little too easy on Donald Trump last time," Paul said in the interview, referencing a heated exchange the two had in an August Fox News presidential debate. "That's given in jest," he added.