Former Senator John W. Warner, a Republican, on Monday endorsed his Democratic successor, Senator Mark Warner, over Ed Gillespie, a past national Republican Party chairman. The Warners are not related. John Warner earned a reputation as a party maverick by bucking the conservatives who gradually won control of the party during his three decades in office. “There are times you must, I think, recognize that certain individuals are superior in their talents and in what they have done and can potentially do for your state,” he said, praising Mark Warner for seeking bipartisan solutions. Mr. Gillespie said in a statement, “I respect Senator John Warner for his service to our country and our commonwealth, and respect his right to support the candidate of his choice in this race.”