Illinois primary could help Romney stake his claim The Republican presidential candidates spent the past week honing their Southern accents and talking awkwardly about their love of grits. With their Southern swing behind them, they will return to the industrial heartland for a potentially pivotal primary Tuesday in Illinois. Illinois is the biggest of the three contests that will be held over the next week, after Saturday's Missouri's caucuses and Sunday's Puerto Rico primary. Given Rick Santorum's strong performance in the South, Illinois becomes the latest state where pressure will be on Mitt Romney to regain momentum. It also offers the former Massachusetts governor the opportunity to extend his winning streak in Midwestern primaries. Romney struggled mightily to beat Santorum in primaries in the two other big Midwestern states, Michigan and Ohio. A Romney victory in Illinois would puncture Santorum's hopes of winning and give the former governor a decisive hold on the GOP nomination. Romney is only narrowly ahead in Illinois, according to the most recent public poll. But that puts him in better shape than he was at comparable times in Ohio and Michigan. In both of those states, he trailed Santorum a week out from the primary and used money and muscle to win. The poll, by the Chicago Tribune and WGN-TV, showed Romney with 35 percent of the vote, followed by Santorum with 31 percent, former House speaker Newt Gingrich (Ga.) with 12 percent and Rep. Ron Paul (Tex.) with 7 percent. But that survey might understate Romney's potential strength, according to a number of Republican strategists. Romney's edge "We start out in Illinois ahead," said a Romney supporter, who spoke on the condition of anonymity to talk candidly about proprietary data. In both Ohio and Michigan, we started out behind and by double digits in both states. Romney had to come from way back to catch Santorum in both states. Here, he doesn't have to do that. Santorum is at a disadvantage in the delegate fight, having failed to qualify a full slate of delegates on Illinois's primary ballot. That hurt him in Ohio as well. Economic issues are likely to dominate the primary campaign in Illinois. The state's unemployment rate is above the national average and higher than in Michigan or Ohio. The state faces significant budgetary problems, despite a tax increase enacted a year ago, and its bond rating is one of the lowest in the country. Despite the economy, Illinois is unlikely to be competitive in November given that President Obama's home town is Chicago and that the state has supported Democratic nominees in the past five presidential elections. But the primary provides another test for the Republican nominees to demonstrate their ability to motivate voters in the kind of big and diverse states that will determine the outcome in the fall - and to make the case about who is best equipped to defeat Obama nationally. A state "in the mix" Illinois Republicans find themselves in an unfamiliar position. The state hasn't hosted a truly competitive Republican presidential primary in more than two decades. This year, their votes will probably help determine who runs against Obama in November.