It appears that Santorum's Super PAC will spend a substantial amount in the Wolverine State:
[I]t’s not as if Romney and his super PAC are about to get outspent on the air overall. But the RWB Fund’s presence in Michigan is going to make it a fairer paid-media fight than Santorum’s had anywhere else this cycle. And the huge, compressed super PAC buy over the next few days means that Santorum won’t be defenseless on the air as the first wave of negative ads against him register among Michigan Republicans.
Dan Hartranft looks at the Red White and Blue Fund's impact in February. Meanwhile, Gingrich's Super PAC is now running a national anti-GOP establishment radio campaign and has launched a new website, TimeToChoose.com. Here's the 30-second version: