Senator Rick Santorum of Pennsylvania has had a good week, winning three states–Minnesota, Missouri, and Colorado–last week.

He had an even better weekend. He went toe-to-toe with David Gregory on MSNBC’s Meet the Press, George Stephanopolous on ABC’s This Week, and CNN’s State of the Union, and they failed to get their pound of flesh. They hit him with everything they had. They even pretended to read his book, It Takes a Family, but they failed to “get” Santorum. He didn’t produce a gaffe because he is comfortable in his own skin.

Santorum Picks His Targets Carefully

Earlier this campaign, Mitt Romney refused to do television interviews. Rick Santorum went on three Sunday shows and did so with ease. Santorum smiles, he laughs at the media’s silly questions, and he answers their reasonable ones. He makes the moral case against Mitt Romney, Barack Obama, and Newt Gingrich, showing that on the issues of the day–government-run health insurance, cap and trade, and the Wall Street bailouts–all three candidates have virtually identical positions.

Together, Rick Santorum and Newt Gingrich have put the “evitable” back in Romney’s supposedly inevitable cruise to the nomination. Romney may yet get the nomination. After all, it is hard to see him losing in the delegate rich states of California (169) and New York (95), for instance, but those primaries are a long way off yet, in June and late April respectively. Still we may actually have a nominee who failed to win a single state in the South and the Midwest if Romney wins the nomination. To say that is unprecedented is putting it mildly. Romney has thus far failed to win a red state and in every state he has won is less popular than when he won it. Interestingly, Romney has lost every single state that Hilary Clinton did in 2008, save the Maine caucuses which he won Saturday. But Romney ought to be worried that Santorum, who didn’t even bother to go to Maine, got 18% of the vote.

The real test for Santorum will be whether or not he can defeat Romney in the state’s that Romney is expected to win, the better if it is considered Romney’s home state. Such a state is Michigan, where according to Public Policy Polling, Santorum is now leading by double digits. Santorum’s message of zeroing out the capital gains tax for manufacturing seems to be working, especially in the areas still hard hit by the recession. This strategy of appealing to the white working class voters that Obama has almost officially abandoned portends well for Santorum and the GOP generally. After all, there are a lot of them in the industrial swing states any Republican will need to beat Obama.

For Romney, the trick will be whether or not he can win the demographics, namely the white working class, that have flocked to Santorum. The question for Gingrich is whether or not he can stop Santorum from coalescing the Not Romney vote. He’s having trouble, especially now that his biggest backer, Sheldon Adelson, has stopped writing his Super PAC checks and his campaign is down to its last $600,000. Mitt Romney met with Adelson last week to try to stop him from backing Gingrich, according to CNN. It apparently worked. Gingrich will have to show that his message can attract more donors and more voters. The flip side of campaign finance laws that would stop CEOs from donating to Super PACs is that sometimes CEOs choose not to donate. A campaign that relies on the generosity of one man’s largesse can find that generosity fleeting, indeed.

UPDATE: A new ARG poll puts Santorum up over Romney in Michigan, too. The former senator from the Keystone state leads the former governor of the Bay State by 6 points (33% to 27%)  Key to its findings? The Tea Party.

Santorum leads with 37% among likely Republican primary voters saying they are supporters of the Tea Party, followed by Gingrich with 29%, Romney with 17%, and Paul with 11%. Among likely primary voters saying they are not supporters of the Tea Party or are undecided about the Tea Party, Romney leads with 35%, followed by Santorum with 30%, Gingrich with 14%, and Paul with 13%.

In other words, Santorum leads among those who were the most fired up over 2010, which can’t be good news for Mitt Romney.