ROBERT SIEGEL, HOST:
Another state, another furious dash to the finish for Republicans competing for the presidential nomination. Illinois holds its GOP primary tomorrow. Former Massachusetts Governor Mitt Romney is looking to increase his delegate lead, and he is still searching for that decisive win over his main rival, former Pennsylvania Senator Rick Santorum.
NPR's David Schaper has been talking with voters in Illinois.
DAVID SCHAPER, BYLINE: We can talk politics in a minute first, how about this weather?
TIM HERR: Oh, it's fantastic, isn't it? It's what, 78 degrees here in the middle of March? It's incredible.
SCHAPER: Forty-four-year old Tim Herr is out for a bike ride with his wife and eight-year-old son in suburban Wheaton, Illinois. And while he's enjoying summer-like heat, Herr is lukewarm about the Republican presidential candidates, saying he's still undecided.
UNIDENTIFIED MAN: I'm leaning a little bit more towards Romney at the moment simply because of his business background. I think that would be something we definitely need in a leader more than the social issues at this point.
(SOUNDBITE OF MUSIC)
MITT ROMNEY: Thank you. Thank you.
(SOUNDBITE OF APPLAUSE)
SCHAPER: Sensing an opportunity on economic issues to put some distance between himself and challenger Rick Santorum, Romney is doubling down in Illinois. He's staying in the state through tomorrow's vote and added more stops. Romney is focusing his attack, though, on President Obama, while touting his own business acumen.
ROMNEY: If you spend more money than you take in, you go broke. So, you know, I learned that for 25 years, so I understand how it works.
SCHAPER: And Romney poked fun at the massive state budget deficit in the president's home state.
ROMNEY: He was a legislator in Illinois where, I understand, if you don't spend more money than you take in, you don't get reelected. Right?
SCHAPER: Romney takes subtle swipes at his GOP rivals, too, slamming them as economic lightweights. His message resonates with 28-year-old Connie Gustafson and her husband Carl.
CONNIE GUSTAFSON: We were undecided until today and I would say that, after hearing Governor Romney today, our decision has been made that – yeah, he will get our vote.
SCHAPER: But some Illinois primary voters aren't buying Romney's message that he's better tested than the others in the real world economy. Forty-five-year-old Karen Mack of Wheaton is turned off by Romney's wealth.
KAREN MACK: I would like to put somebody in office who had to work for a living. The idea that politicians are wealthy and have lost touch with middle class and what the real issues are is disheartening.
SCHAPER: And in the rest of Illinois, beyond Chicago and its suburbs, Republican primary voters tend to be more socially conservative and many still question Romney's conservative credentials.
In Dixon, Illinois, the boyhood home of Ronald Reagan, Aaron Wiles turned out to hear Rick Santorum speak next to the town's Ronald Reagan statue.
AARON WILES: I'm looking for somebody who I think is the true conservative in the race and I have serious hesitations with Mitt Romney's frontrunner status. And I do believe that Rick has been a conservative from day one, ever since he's been in the senate in Pennsylvania, so...
SCHAPER: And that's the message Santorum himself is trying to hammer home to Illinois voters.
RICK SANTORUM: There's one candidate in this race who can never make this race about freedom because he simply abandoned freedom when he was governor of Massachusetts and he abandoned it when he promoted ObamaCare in 2009.
SCHAPER: Santorum has been drawing huge crowds at events like this one in Illinois and he's hoping strong turnout downstate can offset the more moderate Chicago suburbs.
MATT STREB: The wheels on the Romney bike are a little wobbly now. I think, if he loses Illinois, one of them probably falls off.
SCHAPER: Matt Streb, political scientist at Northern Illinois University says, while Illinois is usually a blue state in general elections, Republican primary voters have been trending more conservative in recent years. He says a decisive win in Illinois would certainly go a long way to helping Romney get closer to the nomination.
STREB: We are getting to the point, though, where kind of momentum becomes less important and now delegate count does matter.
SCHAPER: And that's where Santorum could come up short in Illinois. Even if he is able to win the popular vote, Santorum was unable to field full slates of delegates in every Illinois congressional district.
David Schaper, NPR News, Chicago.