After Tonight, What's Next? - NYTimes.com March 13, 2012, 8:24 pm With the contests in Mississippi and Alabama almost over, the candidates will soon shift their attention to Missouri and Illinois. Mitt Romney's campaign has been eying Illinois - which will hold a primary on March 20 - has an opportunity to make a statement in the battle against Rick Santorum. But early polls have suggested the two are locked in a tight race there. And Missouri is an odd case: Mr. Santorum routed Mr. Romney two-to-one in the state's primary in early February and used the momentum from the victory to help fuel his challenge to the front-runner. But that primary was a non-binding affair that is now being followed up by Missouri's official caucus on Saturday, where 52 delegates are at stake - this time for real. Mr. Romney's campaign advisers had argued in February that Mr. Santorum's victories in Missouri meant little. Now, Mr. Romney is campaigning in the state, hoping to capture most of the delegates there. In fact, Mr. Romney spent part of Tuesday in Missouri even as voters in Mississippi and Alabama went to the polls. Illinois could be the next big test for both candidates of their ability to appeal in the important Rust Belt. Mr. Romney and Mr. Santorum demonstrated strength in Michigan and Ohio.