It was no accident that on the night Mr. Paul railed against the N.S.A. for 11 hours on the Senate floor, his campaign sent out a picture on Twitter of Ron and Carol Paul, Rand’s mother, standing in front of a television tuned to C-Span’s coverage of the event. “You might recognize these liberty lovers,” it teased.

There is a flip side to appealing to his father’s base. Rand Paul risks losing support from more mainstream Republicans who always viewed the Ron Paul wing of the party with suspicion. A big part of his campaign strategy has been to work hard to court the Republicans that his father could never convince.

Exactly how to use Ron Paul has been a question the senator’s advisers have debated. So far, he has had very little public role except for appearing onstage at Mr. Paul’s campaign kickoff in April. He did not speak.

Advisers still have no plans to use him regularly, though they say they can foresee asking him to campaign in states like Iowa where the Paul name has resonance.