Santorum was elected and served in the House, then Senate, from 1991 until 2007. He lost reelection in 2006.
http://en.wikipedia.org/wiki/Rick_Santorum
He seems like the perfect candidate, for a decreasing fraction of the center-right voting potential demographic.
He has found a career lengthening niche using the Buchanan-Gingrich model of permanent media entertainer, whereby running or threatening to run is almost mandatory.
I did mean to write Santorum was elected twice to (a statewide election) the Senate. There will be no outstanding candidate in 2016. There will be men of varying positive and negative factors. Santorum has many positive factors. Santorum would motivate social conservatives. The GOP usually picks a nominee who has run for President before. That puts him at the top of the list in my book with Perry, Gingrich, and maybe Romney. Other may list his faults but I see them as only marginally worse than Perry's and marginally better than Gingrich's. I'd love to see a President Walker or President Paul, but history says it's unlikely.
If he's only mildly observant of the Constitution he would be refreshingly better than most of our recent Presidents.