After bitter debate, Romney and Santorum eye Mich.

"Look, politics is a team sport, folks," he said of the measure backed by Republican President George W. Bush and other GOP lawmakers.

In the hours leading to Wednesday night's debate, Romney called for a 20 percent across-the-board cut in personal income taxes as part of a program he said would revitalize the economy and help create jobs. The top tax rate would drop from 35 percent to 28 percent, and some popular breaks would be scaled back for upper-income taxpayers. However, aides provided scant details.

"We've got to have more jobs, less debt and smaller government, they go together," Romney said in an appearance in nearby Chandler.

Santorum's rise in the race has left Paul and Gingrich on the outside looking for a way in.

Paul has yet to win any primaries or caucuses. He is airing an ad in Michigan, though, that challenges the Santorum's claim of taking a conservative line against federal spending.

Gingrich, the former Georgia congressman, is pinning his hopes for a comeback on that state on March 6.

His campaign announced plans Wednesday to buy 30-minute blocks of television time in upcoming primary and caucus states for an infomercial on reducing energy prices.

In all, 518 Republican National Convention delegates are at stake between Feb. 28 and March 6, three times the number awarded in the states that have voted since the beginning of the year. It takes 1,144 to win the nomination.

Fouhy reported from Washington. Follow her on Twitter at www.twitter.com/bfouhy

Follow Kasie Hunt on Twitter at www.twitter.com/kasie