Former Pennsylvania Sen. Rick Santorum announced Monday that he’ll run for the Republican presidential nomination. He’s “in it to win,” he told ABC’s George Stephanopoulos on “Good Morning America.”

That’s kind of a defensive thing to say, isn’t it? Presumably, nomination candidates always enter the race with hopes, even expectations of victory. To stress that point is to risk protesting a bit too much.

But that might be Mr. Santorum’s biggest problem. His White House quest seems quixotic, even in an electoral cycle where the field of candidates has no strong frontrunners.

After all, Santorum is an ex-senator because he lost his 2006 bid for reelection by 18 points. Current polling has him as the first choice of about 2 percent of GOP voters. He’s a strong social conservative in a year when conservatives’ energy seems focused on fiscal issues such as the national debt. More charismatic politicians such as Herman Cain, Michele Bachmann and Sarah Palin (maybe) are competing with him for the same rightward slice of the electorate.

Santorum’s “is an unusual case of presidential fever,” noted University of Virginia political scientist Larry Sabato in a rundown of candidates on his “Crystal Ball” blog earlier this year.

The strength of the fundamentalist Christian vote in Iowa might help Santorum score well in the caucuses there, to be held February 8, 2012. He is also strong in South Carolina, the first state in the South to hold a primary.

But his ardent crusades against abortion and same-sex marriage would be unlikely to win him a majority against President Obama in the general election, and are not what tea party activists are looking for at the moment.

“It is difficult to see how Santorum becomes the nominee,” Professor Sabato concluded.

On the plus side, Santorum right now has only about 43 percent name recognition among Republican voters. That might sound like a bad thing, but it also means he has an advantage – he could yet recruit supporters from the many Republicans who don’t really know who he is.

His Positive Intensity Score – the percentage of voters who know him and have a highly favorable opinion of him, minus those who have a highly unfavorable opinion of him – is 16 percent, according to Gallup. That’s not fabulous, but it’s not too bad. Among announced or likely candidates, Santorum trails only Representative Bachmann and Mr. Cain in this measure. (Their scores are 21 and 25, respectively.)

But as Gallup editor in chief Frank Newport notes, “Rick Santorum is not breaking out from the back at this point, based on our data.” At 2 percent, his ballot support is last among the current or likely candidates that Gallup polls on. Even Cain, a former pizza chain CEO who until recently was virtually unknown, has vaulted past him and is now the choice of eight percent of Republican voters.

Santorum may hope that some of Mike Huckabee’s supporters eventually move to support him. He also appears to plan to woo tea party types with strong anti-Obama rhetoric.

“He’s devalued our currency and he’s not just devalued our currency, he’s devalued our culture,” said Santorum on Monday, when announcing his candidacy from the courthouse steps in Somerset County, Pa.