(CNSNews.com) - “To defeat Barack Obama, Republicans can’t nominate a candidate who relies on outspending his opponents 7-1,” Newt Gingrich said in a written statement Tuesday night, after Mitt Romney easily won the Illinois primary.
The Associated Press reported that Romney and his allies outspent Santorum and his backers by $3.5 million to $500,000, an advantage of 7-1.
Gingrich, who finished last in Illinois, said Republicans need a nominee “who offers powerful solutions that hold the president accountable for his failures.”
"Tonight's win means we are that much closer to securing the nomination, uniting our party, and taking on President Obama," Romney wrote in a campaign email sent late Tuesday.
He urged the party to fall in line behind him, saying, "We are almost there."
With 98 percent of Illinois' precincts reporting, Romney had 47 percent of the vote compared with 35 percent for Santorum, 9 percent for Ron Paul and 8 percent for Gingrich.
Exit polls showed Romney was preferred by voters 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.
Romney won among votes who said they were somewhat conservative or moderate, while Santorum prevailed among those who said they were "very conservative."
Santorum, who hopes to rebound Saturday in the Louisiana primary, told supporters in Gettysburg, Pa., that 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," he said before invoking Illinois-born Republican icon Ronald Reagan, the actor turned president. "Saddle up, like Reagan did in the cowboy movies."
Romney has 563 delegates in the overall count maintained by The Associated Press, out of 1,144 needed to win the nomination. Santorum has 263 delegates, Gingrich 135 and Paul 50.
After the Louisiana primary, 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.
Wisconsin shapes up as the next big test between Romney and Santorum. Republican politics there have been roiled by a controversy involving a recall battle against Republican Gov. Scott Walker and some GOP state senators who supported legislation that was bitterly opposed by labor unions.
Gingrich refuses to drop out of the race, saying his campaign will spend the time leading up to the GOP convention "relentlessly taking the fight to President Obama."
Romney did take the fight to Obama in his victory speech Tuesday night: "We once built the interstate highway system and the Hoover Dam. Now we can't even build a pipeline. I mean, we once led the world in manufacturing and exports -- investment. Today, we lead the world in lawsuits. You know, when we replace a law professor with a conservative businessman as president, that's going to end."
Santorum, speaking in his home state of Pa. Tuesday, said the election is not about who's the best person to "manage" Washington or the economy: "We don't need a manager. We need someone who's going to pull up government by the roots and throw it out and liberate the private sector in America. That's what we need."
(The information in this report was compiled from AP reports and other press dispatches.)