A strong showing in the Chicago suburbs and other urban areas of Illinois helped Mitt Romney to an easy win in the IL GOP presidential primary.

With 99% of precincts reporting, Romney had about 47% to Santorum's 35%. Ron Paul and Newt Gingrich ended up third and fourth polling in the single digits.

More importantly, AP is projecting that Romney will win 44 of the 54 delegates at stake (another 15 delegates will be chosen at a state convention in June).

Chicago Tribune:

"What a night. Thank you, Illinois. What a night. Wow!," Romney said to supporters at his victory party at a Schaumburg hotel shortly after 8 p.m. "Tonight we thank the people of Illinois for their vote and for this extraordinary victory."

Savoring a victory in President Barack Obama's home state, Romney framed the general election as a "defining decision" for the American people. "This election will be about principle. Our economic freedom will be on the ballot. ... It's time to say this word: enough."

Santorum, who had already moved on to his home state of Pennsylvania, told a rally in Gettysburg that he had congratulated Romney but still performed well in Illinois.

"If you look at what's going to happen tonight, we're going to win Downstate, we're going to win central Illinois, we're going to (win) western Illinois," he said. "We won the areas that conservatives and Republicans populate. We're very happy about that. We're happy about the delegates we're going to get too."

The results provided the former Massachusetts governor with a sizable victory and also resurrected the aura of inevitability that his campaign has tried to project, only to be thwarted by close elections and even defeats in other states.

Electability was the most important issue to IL voters and Romney won 70% of those votes. Electing a "true conservative was far less decisive in the primary, hurting Santorum's chances. Santorum also did well among evangelical voters, but only 42% of Illinois voters identified themselves as Christian conservatives.

The exit polls conducted at voting locations around Illinois showed that Santorum also won among voters earning less than $50,000 a year, those without college degrees, and among voters for whom being a "true conservative" or having a strong moral character was the top consideration.

Mitt Romney swept most of the other categories, en route to a popular vote victory.

Now its on to the Louisiana primary on Saturday where Santorum currently has a sizable lead over Romney.