No, many of them did not take sides until the convention, to include Buckley, Thurmond, Tower, Connally, Dole (yes...Dole), Rhodes, etc. But that particular acid test holds true. By the way, in the case of Lott, he was working AGAINST trends in his own state. Had Mississippi held a primary the results would have been the same overwhelming vote for Reagan that Georgia/Alabama/Texas primary voters gave him.
Tower was pro-Ford and was outraged that he was shut out in the May 1, 1976, first ever TX Republican presidential primary. Reagan won all delegate slots, 96, I believe was the number.
I didn’t know that Buckley stayed neutral. But only Helms and Laxalt endorsed Reagan prior to Kansas City in 1976. I think Ron Paul in the House did too.