Story highlights "For 70 years, he's been progressive Democrat," Paul said

"I was never lobbying to avoid questions from a tough questioner," Paul added

Washington (CNN) Republican presidential candidate Rand Paul said front-runner Donald Trump might be better off trying to join the Democrats in a debate, knocking the businessman for his past liberal positions.

"He has brought the debate, the presidential debate, the tenor of the debate to an historic low," Paul told CNN's Alisyn Camerota Thursday on "New Day." "Maybe (he's) afraid of the fact that he's never voted in a Republican presidential primary. For 70 years, he's been a progressive Democrat. I was wondering if maybe he's going to show up for the Democrat primary debate next time."

The senator said Trump wants to avoid discussing his business bankruptcies and desire to expand the power of the presidency.

"I think he does want to avoid difficult questions. And I think he's used to getting his way," Paul said.

The Kentucky senator said Trump's decision to ditch Thursday's Fox News Debate is very different from his own decision to not participate in a recent GOP debate.

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