Romney win in Ill., gives him 541 delegates to Santorum's 253, Gingrich, 135

SCHAUMBURG, Ill. (AP)

Mitt Romney took a major stride toward the Republican presidential nomination Tuesday night, routing Rick Santorum in the Illinois primary for his third-straight big-state win and padding his already-formidable lead in the race for convention delegates.

"What a night," Romney exulted to cheering supporters in suburban Chicago. Looking beyond his GOP rivals, he said he had a simple message for President Barack Obama, the man Republicans hope to defeat next fall: "Enough. We've had enough."

Returns from 61 percent of Illinois' precincts showed Romney gaining 48 percent of the vote compared to 34 percent for Santorum, 9 percent for Ron Paul and 8 percent for a fading Newt Gingrich.

That was a far more substantial showing for Romney than the grudging victories he eked out in the previous few weeks in Michigan and Ohio, primaries that did as much to raise questions about his ability to attract Republican support as to quell those questions.

Santorum, who hopes to rebound in next Saturday's Louisiana primary, sounded like anything but a defeated contender as he spoke to supporters in Gettysburg, Pa. He said he had outpolled Romney in downstate Illinois and the areas "that conservatives and Republicans populate. We're very happy about that and we're happy about the delegates we're going to get, too."

"Saddle up, like (Ronald) Reagan did in the cowboy movies," he urged his backers.

Most recently, Santorum backpedaled after saying on Monday that the economy wasn't the main issue of the campaign. "Occasionally you say some things where you wish you had a do-over," he said later.

Over the weekend, he was humbled in the Puerto Rico primary after saying that to qualify for statehood the island commonwealth should adopt English as an official language.

Initial results showed Romney's victory was worth at least 19 delegates in Illinois.

That gave him 541 in the overall count maintained by The Associated Press, out of 1,144 needed to win the nomination. Santorum has 253 delegates, Gingrich 135 and Paul 50.

Exit polls showed Romney preferred by primary-goers who said the economy was the top issue in the campaign, and overwhelmingly favored by those who said an ability to defeat Obama was the quality they most wanted in a nominee.

In the long and grinding campaign, Santorum looked to rebound in next Saturday's primary in Louisiana, particularly given Romney's demonstrated difficulties winning in contests across the Deep South.

A 10-day break follows before Washington, D.C., Maryland and Wisconsin hold primaries on April 3.

Santorum is not on the ballot in the nation's capital.

Private polling shows Romney with an advantage in Maryland.

Wisconsin shapes up as the next big test between Romney and Santorum, an industrial state next door to Illinois, but one where Republican politics have been roiled recently by a controversy involving a recall battle against the governor and some GOP state senators who supported legislation that was bitterly opposed by labor unions.