Santorum at least took it to Romeny a little regarding health care. He seemed the only one to actually score some points against him.
As for Bachmann, what the heck is up with her and Willard?
It's like she's smitten with Mittens.
Romney can't get above 25% in the polls, so his only path to the nomination is to make sure everyone else stays in as long as possible splitting up the remaining votes. If any single person starts to grab to big of a share of the remaining 75%... he focuses on them while simultaneously building up the others. Romney is playing this like a master. And he is obviously counting on conservatives reluctantly supporting him in the general.