According to an undoubtedly-intentionally-leaked strategy memo from the Mitt Romney campaign, Romney claims he's now the front-runner. Kind of a weak argument, in my view--it leans heavily on the fact that Romney leads in Iowa and New Hampshire (where it just so happens he's advertised heavily). But if you look closer at other data, a different picture emerges. Examples: Giuliani leads in national polls of Republicans; Romney's barely over 10%. Meanwhile, state polls show Giuliani leading in South Carolina; he leads pretty comfortably in Florida; he leads big in California; he leads in Michigan; and he leads big in New Jersey. Romney's camp likes where they are in Nevada, I guess, though the latest poll there actually has Thompson leading.
It's still an open race for the Republican nomination, and nobody has anything locked up; but I think the Romney camp's attempt to steal some momentum by claiming to be the new front-runner just won't stand up to scrutiny.