Illinois Republicans are voting in their state's "critical" presidential primary on Tuesday, and Mitt Romney appears headed for a "blowout victory," according to Public Policy Polling. In the firm's latest poll, the former Massachusetts governor leads with 45 percent, while his nearest rival, Rick Santorum, has just 30 percent, and Newt Gingrich and Ron Paul trail far behind. Will Illinois help cement Romney's edge, or will voters defy predictions? Here, four factors at play:

1. Romney is finally winning over the conservative base
Nationally, Mitt has gathered "essential momentum" with the "party's staunchly conservative base," says Jon Cohen at The Washington Post. Santorum is still the favorite of the far Right, but Romney is now "more competitive." Sixty-four percent of the most conservative voters have a favorable view of Romney, up from a low of 43 percent just three weeks ago. If Romney can win a hefty portion of the party's base in Illinois, he might "settle stubborn issues" about his ability to unite the party — issues that were exacerbated by Mitt's third-place finishes in deep-red Alabama and Mississippi.

2. But Santorum's not out of it yet
Don't be fooled by the polls, says Reid J. Epstein at Politico. "Illinois remains in play." Yes, "Romney has a roster of blue-chip GOP supporters" in the moderate Midwestern state, which "seems a good fit to his brand of Republicanism." But Romney's supporters are "more nervous" than the evidence suggests they should be. Why? As in other states, Romney has "failed to generate sufficient excitement" in Illinois, and many voters just don't feel a "spark" with Romney. If passionate Santorum supporters flood the polls, the Pennsylvanian might just be within "striking distance" of an Illinois win.

3. Regardless, Mitt will dominate the delegate haul
Even if Santorum pulls off an upset, Romney is likely to win the biggest share of the state's "hefty" prize of 69 delegates, says ABC News. Santorum's organizationally challenged campaign failed to get him on critical delegate lists in four of the state's 18 districts, making him "ineligible" for at least 10 delegates. Indeed, says Nate Silver at The New York Times, I'd be surprised if Santorum won more than one-third of Illinois' delegates.

4. The real question is what happens next
Romney's overwhelming victory in Puerto Rico over the weekend wasn't enough for him to seal the deal, and on its own, Illinois won't be either, says Ed Morrissey at Hot Air. The recent suggestion from Romney's wife, Ann, that other candidates drop out and "come together" to defeat President Obama is premature. But if Romney manages to deliver the big win polls predict for him in Illinois, and pull off his first win in the South on Saturday in Louisiana — "which looks like a toss-up" — then Ann "might have a case."