The presidential field may be wide open, but one candidate is playing the role of the inevitable front-runner, as his performance at the Conservative Political Action Committee Conference this weekend shows. Former Massachusetts Gov. Mitt Romney brought with him to the event a large entourage that stayed for several days, while most other potential candidates dropped in and out of the conference to make their speeches and headline a reception or two. Other serious contenders brought just a few key staffers, but many didn't even have their top political aide in tow. Former Alaska Gov. Sarah Palin and former Arkansas...