In past presidential races, the tell-tale sign of a candidate quitting the race was if said candidate was running out of money. Typically, a campaign would start running out of money once its candidate started losing. And when the money dried up, the candidate humbly bowed out.

That rule of thumb seemed as if it had been thrown out now that super PACs have joined the game. Now it doesn't matter how much a candidate loses. Candidates can lose primaries, debates, momentum, focus, but still keep right on trucking as long as they have someone willing to pour more money into the right super PAC.

And so we have seen this year a pack of Republican presidential contenders who say they have no intention of getting out of race -- despite loss after loss after loss -- until it's convention time. It's less about not liking their GOP rivals and more about the potential of an unlimited income stream from these super PACs. As long as a candidate has a war chest, the war will continue.

Of the four Republicans still in the race, one candidate is hinting at a new strategy: Sunday we heard that maybe Newt Gingrich won't take his fight all the way to the convention. Maybe Gingrich will fight on only until frontrunner Mitt Romney gets the required number of delegates needed to win the nomination -- something political insiders say is a likelihood come early June.

Why the change in Gingrich's heart? Yes, he's out of money.

Gingrich acknowledged on Sunday that his campaign was in debt. And by "debt" we're talking spending roughly $4.5 million more than the campaign has raised. Gingrich said he had to borrow from his personal finances to help fund his campaign.

The former U.S. House speaker said he would remain in the race to drive the party in certain ideological directions. Gingrich also pledged to help Romney once he reached the necessary number of delegates. He added that there would be no lingering animus between him and Romney.

Sounds like he's got his eyes on a graceful exit. What do you think? Should Gingrich get out of the race?