WASHINGTON — With the debate over the federal deficit roiling last year, David Smick, a financial market consultant, held a dinner for a bipartisan group of connected budget thinkers at his expansive home here.

At the table were members of the city’s conservative policy elite, including Alan Greenspan, the former chairman of the Federal Reserve, and William Kristol, the editor of The Weekly Standard.

But that evening, none drew more attention than a relatively new member of that best-of class: Representative Paul D. Ryan, Republican of Wisconsin and now Mitt Romney’s running mate, who spoke passionately about the threat posed by the national debt and the radical actions needed to rein it in.

“I thought, ‘This is the one guy in Washington paying attention,’ ” said Niall Ferguson, the Harvard economic historian and commentator, who spent some of the rest of that evening, along with Mr. Kristol, trying to persuade Mr. Ryan to run for president.