Schaumburg, Ill. ? Mitt Romney took a major stride toward the Republican presidential nomination Tuesday night, routing Rick Santorum in the Illinois primary for his third big-state win in a row 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 75 percent of Illinois’ precincts showed Romney gaining 47 percent of the vote compared to 35 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.

Romney triumphed in Illinois after benefitting from a crushing, 7-1 advantage in the television advertising wars, and as his chief rival struggled to overcome self-imposed political wounds in the marathon race to pick an opponent to Obama.

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.

Initial results showed Romney’s victory was worth at least 22 delegates in Illinois.

That gave him 544 in the overall count, out of 1,144 needed to win the nomination. Santorum has 253 delegates, Gingrich 135 and Paul 50.