Santorum, Romney jockey for position in Mich.

Rick Santorum was responding to remarks made by a wealthy supporter Friday, and he picked up new support as he surges toward what he hopes will be front-runner status in the race for the Republican presidential nomination.

It comes as Michigan prepares to host the nation's next presidential primary, on Feb. 28.

Santorum began his Friday distancing himself, on "CBS This Morning," from controversial birth control comments made by financial campaign benefactor Foster Friess, saying "I'm not responsible for every comment that a supporter of mine makes. ... It was a bad joke, it was a stupid joke."

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Not long after, Friess apologized, writing on his website, "My aspirin joke bombed. ... To all those who took my joke as modern day approach, I deeply apologize and seek your forgiveness."

Looking to change the subject, Santorum appeared with Ohio Attorney General Mike DeWine, who switched his endorsement from Romney to Santorum.

Stumping in Idaho, Mitt Romney appeared sufficiently worried about the Santorum surge that he's finally taking off the gloves.

"I hope people take a very close look at his record," Romney said at one stop, portraying Santorum as a big spender when he was in Congress. "He voted for billions of dollars of earmarks, including the 'Bridge to Nowhere."'

And Romney's campaign released its first attack ad on Santorum in Michigan, a state where Romney was - until recently - considered the favorite son.

The Romney campaign is now planning to do to Santorum in Michigan what it did to Newt Gingrich in Florida: Use its huge bank account to bury Santorum in negative ads.

To see Chip Reid's report, click on the video in the player above.

Also, Republican Rep. Bill Huizenga of Michigan, a Romney supporter, told "CBS This Morning: Saturday" co-host Rebecca Jarvis he's confident Romney will win in Michigan, but even if he doesn't, Romney can go on to grab the GOP nod. To see that interview, click on the video below: