Santorum couldn’t even win a senatorial election in his home state of Pennsylvania.
Remember the rest of the story: He lost in a horrible year for Republicans, while running against a fairly conservative Democrat who was the son of a prominent conservative pro-life Democratic governor who had major run-ins with the Democratic Party over abortion.
Newt Gingrich has had his own losses in his history. Politicians sometimes lose races; that's what elections are about. Santorum has a history of winning difficult races in Democratic-leaning districts while being an outspoken pro-life conservative, and that counts with me.
I personally wish Santorum had run for governor of Pennsylvania, won, and then run for president a few years from now with executive experience under his belt and a record of winning. His Pennsylvania loss definitely makes him a weaker candidate but doesn't rule him out entirely, especially given the circumstances.