Michael Tomasky thinks there may be room for one more in the Iowa caucus race — a candidate who can connect with Iowa conservatives on policy and record while having the credibility to compete against Mitt Romney and Newt Gingrich.  And who might that be?  The man who has spent almost all of his time among those conservatives in this race:

From the “predict something long enough, and it’ll happen eventually” department, I was delighted to see in this new PPP poll not only that Newt Gingrich tanking but also that my man Rick Santorum has made it to the promised land of double digits for the first time, at exactly 10 percent. A modest start, but then again, every big thing starts small; Christianity was illegal for 300 years. So I still submit, as I’ve argued before, that Santorum has the ability to shake up the race. …

There is still time for one more non-Mitt to get his shakedown cruise, even before Iowa. Santorum has several points going for him. As I’ve noted previously, he’s kosher with all three wings of the party, neocons, theocons, and pluto-cons. He’s the only candidate who has campaigned feverishly across the state. It’s become conventional wisdom that that doesn’t matter anymore. But how did that become conventional wisdom? In part it became conventional wisdom on December 7, when Dick Morris said on the set of Fox & Friends that Iowa is won “on this couch.” I haven’t put much stock in Dick’s predictive powers since 1999, when he kept insisting in his New York Post columns that Hillary Clinton would never actually run for U.S. Senate in New York, and I challenged him during a ride on the #1 train to put some money on the proposition, and he wouldn’t. It’s possible that Morris is a pious man like Rick Perry and therefore averse to betting, but I doubt it. So it could be that the new CW is wrong, and Iowa can still be won . . . in Iowa.

Tomasky gives what he sees as Santorum’s only downside:

Santorum has one big down side. He lost his last election by a whopping 18 points. That’s bad. There just isn’t much history of people coming off losing races and then doing well in pursuit of the presidency. In fact there is probably no history of it. On the other hand, he did serve two terms as senator in a blue state, beating an incumbent Democrat (Harris Wofford) to get there in the first place. He might not win Pennsylvania in a general election, but it’s not out of the question, and at the very least he’d sure make the Obama campaign spend time and money there that it would rather put into Ohio. I think that if I were a Republican insider pondering what the map might look like next November 7, I’d rate the matter of his provenance a plus, maybe a big one. He’s sure more likely to contest Pennsylvania than Romney is Massachusetts—or even Michigan, a state from which he’s many years removed.

Had Santorum retired in 2006 rather than lose re-election, the comparison to Romney would be more apt.  However, I think Tomasky’s right that Santorum would do better in Pennsylvania in 2012 than Romney would in Massachusetts, although the better question would be whether Santorum would do better than Romney in Pennsylvania.  Democrats cannot afford to lose Pennsylvania in a presidential election, and a native son might be better equipped to carry the state than Romney, although it’s possible both would beat Obama there in any case.  If that happens, the entire Rust Belt would probably go Republican, and Obama would go back to Chicago.

Santorum has another problem as a potential boomlet candidate — resources.  Rick Perry is making a big play in Iowa with media buys, trying to accomplish exactly what Tomasky predicts will happen for Santorum, and Romney is also flooding the airwaves.  Santorum can’t compete with that directly, but he’s hoping that his ground work will trump the ad wars.  He might get a side benefit from Perry’s attack on the two frontrunners, though.  If Perry undermines support for Gingrich and Romney but doesn’t make the sale that he’s a reliable, competent alternative, voters who have seen a lot of Santorum might give the real underdog some extra consideration.

These are long-shot predictions, but they’re not out of the realm of possibility.  Santorum is one of only two check-box conservatives still left in the race, and Michele Bachmann created a credibility crisis for herself this fall.  Santorum improved his debate performances in December, looking presidential and scoring points on foreign policy (as did Bachmann).  Is that enough without a big campaign warchest?  We’ll soon see.

I’ll be speaking with Senator Santorum on today’s Ed Morrissey Show, which starts at 3 pm ET.  Don’t miss it.

Update: Santorum scored a big endorsement a few minutes ago:

Two weeks before the Republican nominating contest opens at the Iowa caucuses, former Senator Rick Santorum of Pennsylvania has won a highly-coveted endorsement from one of the state’s social conservative leaders.

Bob Vander Plaats, who has sought to put his imprint on the Republican presidential race for months, announced Tuesday that he would support Mr. Santorum. He and other evangelical Christians have talked openly about theirstruggle to unite behind one candidate, but he urged others to follow his lead.

According to this report, this is a personal endorsement from Vander Plaats, not an organizational endorsement from The Family Leader, the group founded last year by Vander Plaats.  Still, it will draw some needed attention and earned-media coverage for Santorum, and might be a spark among conservatives to give him a chance.