Rick Santorum is learning what it feels like to be Newt Gingrich.

Following a hefty beat-down of Gingrich in advertising placed by Mitt Romney surrogates, the former Massachusetts governor is coming off a decisive victory in the Nevada caucuses to set his sights on the next caucus states of Colorado and Minnesota.

And with Santorum showing some resiliency in Minnesota -- polling better than Romney in the most recent survey -- the Romney campaign is now targeting the former Pennsylvania senator.

On a conference call Monday morning, former Minnesota Gov. Tim Pawlenty, a national co-chairman for the Romney campaign, said of Santorum: "If you look at his record, it’s not a perfect conservative record by a long shot."

"As a U.S. senator, he was a leading earmarker and pork-barrel spender," Pawlenty said of Santorum in a follow-up press release aimed at conservative Minnesota voters.

Displeased with the additional focus from the Romney camp, Santorum said the attack won't impact him the way it did the former House speaker.

"This is typical Romney," Santorum said at a media event in Minnesota. "He goes out and throws the kitchen sink and runs negative ads and sends out his surrogates to rip and tear even though he is as vulnerable on this issue as anybody.

"I don't think it's going to work this time," he said.

Santorum countered with his own attack on Romney's record.

"When Governor Romney says he didn’t increase taxes in Romneycare, the answer is yes he did, your taxes. Because you here in Minnesota are paying a disproportionate amount of money out of the Medicaid system to the state of Massachusetts to fund their expansion of their health care program," Santorum said during a speech on health care in Rochester, Minn.

Asked about the new focus on Santorum's record, Pawlenty made no bones about the strategy.

"Rick has got a credible campaign, he’s shown some levels of support beyond what was a third or fourth place finish in recent states," he said. "He’s a credible candidate and he deserves to be right in the middle of the back and forth between the campaigns."

Fox News’ Alex Rivera contributed to this report.