Conventional wisdom has it that Gingrich has been out of the running for some time (though his strongest state, Georgia, votes on Super Tuesday), while Santorum has emerged as the most viable conservative option to Romney.
Recent polls indicate that momentum is not in his favor, and Super Tuesday could be a tough night for him.
Gingrich, meanwhile, seems to be gaining momentum in the Southern states – not just in Georgia, which he is all but certain to win, but also in Tennessee and Oklahoma, where he could come in second to Romney.
Such a strong result would certainly give Gingrich (who has already declared he’s in it for the long haul) motivation to stay in the race – especially since the next states to vote are in the South.
Most likely, Santorum will stay in as well, even if it's a disappointing finish, but if he’s unable to win a single Super Tuesday state beyond Oklahoma (which is expected) he may have a hard time justifying his run much longer.