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Sen. Rand Paul (R-Ky.) continued his proto-presidential campaign against Hillary Clinton over the weekend, wondering aloud in an interview with Politico whether the former secretary of state might be too old to handle the physical demands of running a national campaign.

Paul "none too subtly" raised Clinton's age in the interview, as Politico put it.

"I think all the polls show if she does run, she'll win the Democrat nomination," Paul said. "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."

Clinton is 67 years old, and should she run for president, she'd be a little younger than Ronald Reagan was when he took office.