WASHINGTON  It was Thanksgiving break of 1998 at Capital University Law School in Ohio, and Senator Mitch McConnell was on the phone for Prof. Bradley Smith.

Mr. McConnell’s aides had already approached the conservative law professor about a spot on the Federal Election Commission, but Mr. Smith was hesitant. Now the senator himself was calling, and he was not going to be turned down.

“Here was Senator McConnell lobbying me to take the job,” Mr. Smith recounted with a laugh. “He was saying that we’re getting hammered by the left as lackeys for big money, and we needed someone who could begin to make the intellectual case for deregulation in Washington.”

Mr. Smith’s conservative writings  he saw campaign finance restrictions as largely unconstitutional and favored abolishing the election commission itself  were sure to provoke controversy. But Mr. McConnell, a scrappy politician who has long reveled in his reputation as the “Darth Vader” of campaign finance, made clear that he welcomed a good fight, Mr. Smith said. “I owe him a lot,” he said.