Mr. Paul will join former New York Mayor Michael Bloomberg’s Partnership for a New American Economy’s monthly series on immigration reform hosted by Grover Norquist.

Mr. Paul, who is openly considering mounting a 2016 presidential campaign, opposed the Senate bill and the prospect of “amnesty.” Mr. Bloomberg is, of course, one of the leading proponents of immigration reform, which the Partnership for a New American Economy aims to promote.

“He’s just going to talk generally about his ideas that he pushed in the Senate bill and some of the problems with the Senate bill and why it made so difficult to pass,” said Mr. Paul’s spokesman, Brian Darling. “There’s not going to be anything different in his message tomorrow that he hasn’t said already a million times.”