If the roles were reversed...

[Insula Dei]

... and Santorum was the likely frontrunner, what would polls be like? Would the race even still be on by now?

[Lincoln Republican]

Unlike the antics Santorum is pulling, if the roles were reversed, with Santorum by all accounts becoming the nominee, Romney would have been intelligent enough to realize this, and would have had the decency like he did in 2008, he would have withdrawn from the race, probably after being crushed in Illinois, let's say, and would have endorsed Santorum for the sake of party unity.

Santorum is simply too arrogant and too self centered to do the decent and right thing and withdraw and support Romney to unite the party behind the nominee, as by now, Santorum knows full well there is absolutely no way he is going to get the nomination.