"When we say over and over someone can't win, that is a form of rigging in the sense that it is designed to suppress turnout," Paul said in an interview on "The Tom Roten Morning Show" picked up by CNN KFILE.
He cited polling in the 2015 race for governor in Kentucky as an example of polling that didn't accurately predict the outcome of the election.
"The polls are put out, you know to make it either look closer than it is or to make it look like Democrats have a better chance," Paul said. "And I think it's done by design to try to dampen turnout."
But Paul didn't commit to a defense of Trump's claims that the election will be rigged, saying that he was "not sure exactly" what Trump meant and didn't necessarily agree with him.
Trump has repeatedly claimed that the election will somehow be rigged against him and that polls showing Clinton in the lead are inaccurate and aimed at suppressing GOP voter turnout.