Obviously Rick Perry will go into the Political Gaffe Hall of Fame, but of the remaining two front runners, who has been most hurt by gaffes/controversial statements?
One could argue that Romney is constantly feeding his own stereotype of an out of touch elitist with talk of knowing team owners, not caring about the poor, letting housing "bottom out", not making much money, couple of Cadillacs, etc. And his regular foot in mouth moments are why he hasn't closed the deal. There is probably some truth to that.
However I would argue (
as would Charles Krauthammer) that Santorum squandered his big moment after he surged to the top of the polls after his three state shutout in February. He was leading going into MI (a Romney home state) but he got off message and on about "College, Kennedy and Contraception" and lost MI, which I think was his last chance at a "game changer". And this last week in PR is yet another example of a self-inflicted wound that will likely hand all the delegates over to Romney.