By Larry Kane

PHILADELPHIA (CBS) – In Campaign 2012, a big state is on the agenda tonight, a state with a population base similar to Pennsylvania.

Illinois’ population is 12,869,257 — several thousand off of Pennsylvania’s total. The Chicago area vote will determine tonight’s election, and experts will be looking at tonight’s outcome to try and figure out what happens in Pennsylvania five weeks from today.

kane larry tight Analysis: Illinois Primary Could Foretell Result In Pennsylvania

(KYW's Larry Kane.)

The most interesting question in this race is why Newt Gingrich is still in it? Unless he’s waiting until the right time to embrace Santorum.

Right now, Romney has 516 delegates, but if you add up Santorum, Gingrich and Ron Paul, the combined delegates are just 85 away from Romney.

In the past week, Rick Santorum narrowed Mitt Romney’s lead to six points in Illinois, but then the Santorum campaign ran out of gas and money for ad time, and Romney is seen as a big favorite. But, if Romney wins more delegates than Santorum, that could be balanced out by a possible Santorum win in Louisiana on Saturday.

If this were winner-take-all, Romney could have this locked up by May, but it’s proportional voting. That’s why it might not end until June or later.

On the money front, Santorum is being outspent six-to-one in Illinois. But, Pennsylvania, on April 24th, will be different. Of course, if Santorum loses his own state, it could be a crusher.

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