The fight over the Republican Party¿s soul

Coming off a crushing, self-inflicted disaster in Puerto Rico, Rick Santorum knows there's a lot more at stake in Illinois today than just 69 delegates.

"If we're able to do what I know most people think is impossible - carry the state of Illinois - it would fundamentally change this election," Santorum told a crowd of supporters at a rally in Moline, Ill., on Monday. "It will put us in the position where they'll stop talking about delegates and start talking about how to stop Rick Santorum from being the nominee."

He's right. A win in Illinois would be a definite game-changer. The problem is, he's also right that going into the Illinois primary today it does look pretty impossible - unless Mitt Romney were to drop out of the race before the actual voting began.

Still, comparing the Republican primary race to a roller coaster doesn't come anywhere near how jarring, jolting and downright unpredictable it's been. This has been more like an off-road ride across bare rocks in a car with no shocks.

The only thing that's certain is that the Republican base, the folks actually casting the votes, is massively divided. Hard-core conservatives, tea partiers and evangelicals love Santorum. More moderate Republicans, the GOP establishment and rich people love Romney.

This is more than a fight to pick the party's nominee. This is a fight over the party's soul.

And as much as Mitt Romney wishes the rest of the field would just go away (believe it or not, Newt Gingrich and Ron Paul are still in the race - although they're drifting further and further to the sidelines.), he just can't seem to gain enough momentum to force them out of the running.

Instead of a victorious, regal strut to his inevitable coronation as the nominee at the Republican National Convention in Tampa in August, Romney's had to stumble and claw his way through a mud-slinging, state-by-state slog.

And the only thing that seems to be keeping him in the lead is his (or, more accurately, his super PAC's) money, and the relentless stream of negative ads he and the PAC have unleashed on Santorum.

The campaign did it again Monday, when it released video of Santorum speaking in favor of Romney in 2008. It's introduced by the printed words: "Rick Santorum says he's a man of principles. In this case, he's right."

Then it shows Santorum speaking, with Romney standing beside him.

"This is Rick Santorum. I think everybody knows nobody puts words into my mouth," Santorum says. "The words out of my mouth were that if you want a conservative as the nominee of this party, you must vote for Mitt Romney."

Two weeks ago, polls put Santorum and Romney in a dead heat in Illinois. That was right after Super Tuesday, and before Santorum hit with two powerful wins in Alabama and Mississippi that raised more questions about Romney's strength as a candidate.

Santorum was on a roll.

The latest polls, though, show Santorum sliding to as much as 15 percentage points behind Romney.

It might not be that ugly by the time all the votes are counted. Or it may be. But whatever the outcome, it won't end the race, or the divide in the Party.

Santorum is already focusing on the solid conservative support in Louisiana's Bible Belt to boost him to a strong win there on Saturday. The latest poll there shows him with a slight lead, which he's trying to cement by appealing to bayou evangelicals. Sunday, he appeared at controversial pastor Dennis Terry's church in Baton Rouge.

Which fits his strategy: While Romney focuses almost exclusively on the economy, Santorum's campaign themes are about social conservative values - from contraception and abortion to separation of church and state.

And Santorum isn't trying to win the race; he's just trying to keep Romney from getting the 1,144 delegates he needs to get the party's nomination. That way, he can force the discussion over the party's core philosophies on the convention floor.

On Monday, he raised the specter of a brokered convention and a floor fight to pick the party's nominee.

"The convention will nominate a conservative," Santorum said on the "Early Show" on CBS. "They will not nominate the establishment moderate candidate from Massachusetts. When we nominate moderates, when we nominate a Tweedledum versus Tweedledee, we don¿t win elections."