One, Romney has nothing to do with this Super PAC.
Mitt Romney on his Super PAC:
"Well, of course it's former staff of mine. And, of course they're people who support me."
The notion that Romney "has nothing to do with the Super PAC" is an egregious untruth. The law states that the Super PAC cannot take direct orders from the Romney campaign. However, the Super Pac can, and does, coordinate its ads with the Romney campaign by reading accounts of Romney's campaign strategy repeated in the press.
Romney could say today, "Negative attacks against fellow Republicans are unacceptable!," and the Super Pac would desist tomorrow without violating any laws regulating super PACs.
There is a wink and nudge in the attacks against Santorum, and, you know it!