John McCain and Mitt Romney set their sights on next week’s Super Tuesday voting contests following a bitter sparring match Wednesday night over Iraq, immigration and the economy.

Tension between Florida primary winner McCain and runner-up Romney dominated last night’s debate in Simi Valley, Calif. Former Arkansas Gov. Mike Huckabee and Texas Rep. Ron Paul also took part.

McCain, the Arizona Senator, again accused Romney of setting a timetable for withdrawal of the U.S. from Iraq, a charge Romney denied.

“I do not propose, nor have I ever proposed, a public or secret date for withdrawal,” Romney said.

John McCain also said “we may have to go further” to stimulate the economy, in connection with a statement about the stimulus packages making their way through Congress.

McCain and Romney sparred early and often.

Romney said he supported President Bush’s first-term tax cuts. “I believe in getting rates down,” he said. “I think that builds our economy.”

John McCain and Mitt Romney are locked in what has now become largely a two-man race for the Republican nomination.

Huckabee won Iowa’s caucus January 3 but hasn’t won another contest, while Paul remains in single-digits polling-wise. On Wednesday, former N.Y. City mayor Rudy Giuliani quit the race and endorsed McCain.

The intangibles would seem to strongly favor McCain here, but Romney has something in his arsenal McCain cannot match: money.

In Florida alone, Romney was able to air 4,475 ads compared to McCain’s 470 - and Romney’s air power is likely to dwarf McCain’s on Super Tuesday, an advantage McCain will try to counter with free media.

Today, McCain is beginning campaigning San Francisco. Later, he’s expected to pick up another endorsement - California Gov. Arnold Schwarzenegger - then finish the day at a fund-raiser in L.A.

Mitt Romney, meanwhile, is canvassing the southern part of the Golden State with four appearances set for Thursday.