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Mitt Romney and his wife Ann celebrate their victory in the Illinois GOP primary at the Renaissance Schaumburg Convention Center Hotel on Tuesday.
Updated at 6:44 a.m. ET – Mitt Romney won the Illinois Republican primary with ease on Tuesday night, allowing him to grow his delegate advantage over his rivals in the fight for the party's presidential nomination.
The primary had offered Republicans maybe their best chance yet of a genuine one-on-one battle between the former Massachusetts governor and Rick Santorum, his chief competitor for the nod.
"Elections are about choices. And today, hundreds of thousands of people in Illinois have joined millions of people across the country to join our cause," Romney told a throng of supporters in the Chicago suburb of Schaumburg.
As a result of the Illinois vote, Romney's delegate tally rose, though the state-wide popular vote had no technical bearing on the eventual allocation of delegates.
In Illinois, voters elect delegates separately on candidates' behalf.
A total of 54 delegates were at stake on Tuesday, and NBC News projected as of 6:30 a.m. ET that 41 went to Romney and 10 to Santorum.
Check out NBC's Decision 2012 delegate tally here
Still, the primary, held in President Barack Obama's adopted home state (typically a Democratic stronghold in the general election), gave Romney a chance to further his campaign's case that he is the inevitable Republican nominee. He achieved his victory with a similar coalition of voters that had tended to support him in previous caucuses and primaries.
Romney show signs of strength as Republicans begin to coalesce
The ex-governor ran better with more affluent and educated voters, as well as moderates and voters who described themselves as "somewhat" conservative. Thirty-five percent of primary voters said in exit polls that a candidate's ability to beat Obama was most important to them; Romney won 71 percent of those voters to Santorum's 17 percent. Similarly, 58 percent of primary voters said the economy was their top issue, and Romney bested Santorum among those voters by a 17-point margin.
GOP presidential candidate Mitt Romney delivers remarks to his supporters following his win in the Illinois primary.
Santorum continued to outperform Romney among downscale and less educated voters, along with the most conservative Republicans and evangelical Christians.
'We don't need a manager'
He emphasized his ideological steadiness versus Romney in remarks on Tuesday evening, deriding Romney by implication as a timid manager of the status quo.
"This is an election about fundamental and foundational things," he said from Pennsylvania. "This is not about who's the best person to manage Washington. We don't need a manager."
The difference in Tuesday's primary was that these voters made up a smaller share of the electorate than in states like Mississippi and Alabama -- the conservative hotbeds Santorum won last week.
First Read: Illinois isn't Alabama or Mississippi
Despite Romney's victory, the Republican race appeared poised to stretch on at least weeks longer. Former House Speaker Newt Gingrich has shown no willingness to leave the race, and Santorum's campaign has circulated its delegate math, which focuses on halting Romney's march to gather the 1,144 delegates needed to secure the nomination.
This would spark a contested convention when Republicans meet to formally make their nomination in August.
Presidential candidate Mitt Romney has focused almost exclusively on President Barack Obama in recent days instead of the other GOP candidates. NBC's Peter Alexander reports.
According to NBC News projections early Wednesday, Romney had won 485 delegates. Santorum had accrued 193 delegates, while Gingrich had won 137 and Paul had received 34.
The Santorum campaign made its case to reporters on Tuesday why 1,144 was still an attainable goal for the former senator, though he would have to perform especially well in future contests in order to best Romney.
For Santorum, the Illinois primary had meant an opportunity to again upset Romney in a Midwestern nominating contest the frontrunner had been expected to win. Santorum battled the former Massachusetts governor closely in both Ohio and Michigan, but Romney's superior campaign organization and finances -- combined with millions in ads bought by a supportive super PAC -- ultimately carried the day.
© Sarah Conard / Reuters / REUTERS
Mitt Romney holds a town hall meeting at Gateway Convention Center in Collinsville, Ill., on March 17.
But Romney started to pivot toward his general election target -- President Obama -- in his victory remarks on Tuesday evening. He only referenced his Republican challengers so as to congratulate them on a hard-fought campaign. He used the rest of his speech to test themes of his argument against the president.
"This election will be about principle. Our economic freedom will be on the ballot," he said. "I'm running for president because I have the experience and vision to get us out of this mess."
Romney was able to carry momentum into Tuesday's contest resulting from a commanding victory in last Sunday's Puerto Rico primary, which not only won him 20 delegates, but also raised questions about the prudence of Santorum's decision to campaign in the territory -- an expensive commitment which won him no delegates, and only a small share of the popular vote.
Andrea Saul, press secretary for the Romney campaign, previews Tuesday's primary and talks about the delegate tally.
Organizational issues that had dogged Santorum in Ohio's primary also re-appeared in Illinois, where he failed to file the required delegate slates in four congressional districts, meaning he was ineligible to win 10 delegates.
The campaign turns next to Saturday's caucuses in Louisiana. Gingrich, who again vowed to fight onward to Republicans' convention in Tampa this August, spent the day in Louisiana. Santorum also heads next to Louisiana.
The next batch of contests are on April 3 in Wisconsin, Maryland and Washington, D.C.