But Romney said on NBC's "Meet the Press" that Hillary Clinton will be judged on her own merits.
"I don't think Bill Clinton is as relevant as Hillary Clinton if Hillary Clinton decides to run for president," the 2012 GOP presidential nominee said. "I think her record is what will be judged upon, not the record of her husband."
Romney added: "I think Hillary Clinton, if she becomes the nominee, will have plenty to discuss about her own record. I don't imagine that Bill Clinton is going to be a big part of it."
Romney, though, said that Bill Clinton "embarrassed" the nation with his behavior.
"But I don't think that's Hillary Clinton's to explain," Romney said.
Paul has been careful not to directly attack Hillary Clinton for her husband's affair, focusing on the issue more as a counterpoint to Democrats' allegations that the GOP is waging a "war on women." But the attacks suggest Paul might focus on the issue as a fellow 2016 presidential candidate.
As for his own potential 2016 candidacy, Romney continued to say that it's not happening.
Despite his repeated denials, Romney backers continue to push the idea that he might run again -- including in a Boston Globe piece this weekend.
“I'm not running for president," Romney said. "I'm looking forward to supporting someone who I think will have the best shot of defeating whoever it is the Democrats put up.”
When it was noted that Ronald Reagan ran for president three times, Romney had a witty retort.
"I'm not Ronald Reagan," Romney said. "I think that's been pointed out to me before."