* Senior aides say Obama wants "big deal" before year-end
* House Speaker Boehner repeats vow not to raise taxes
By Thomas Ferraro
WASHINGTON, Nov 5 (Reuters) - If President Barack Obama wins re-election, he's expected to move quickly, perhaps within a day, to renew his bid for a bipartisan deal to avert a "fiscal cliff" that threatens to push the United States into recession, top Senate Democratic aides said on Monday.
A victorious Obama could reach out to Republicans as early as Wednesday and pledge that, with the election decided, it's time to find common ground to deal with the year-end expiration of Bush-era tax cuts and the launch of automatic spending cuts that would suck $600 billion out of the economy in 2013.
"He wants to get the process started immediately," one aide said. "We could move quickly," another aide said, explaining that the basic ingredients of any deal - increased tax revenues coupled with cuts in entitlement programs - have been debated thoroughly for the past two years.
"Everyone knows what needs to be done," he said.
Two Democratic aides said White House officials have discussed the matter with top Senate Democrats, though it remains unclear exactly how a re-elected Obama would proceed.
But as one aide said, the White House intends to move quickly because it "wants a big deal" before the current Congress adjourns in December. The White House had no comment.
If Republican challenger Mitt Romney wins, much of the work on a deficit-reduction deal that replaces the automatic cuts and reforms the tax code could be largely delayed until he takes office on Jan 20.
But Republicans in Congress would quickly launch an effort to delay the cuts and keep tax rates unchanged for six months to a year to buy time for a comprehensive tax reform deal.
House Speaker John Boehner said on Sunday that he would angle for a temporary "bridge" to allow the new administration and the next Congress to craft a solution.
"I would think that would be the best you can hope for, and even that is going to be very difficult to do," Boehner, a Republican, told CNN in an interview in his home state of Ohio.
The Democratic aides said a deficit reduction deal would likely contain many elements from one that Obama and Boehner, the top U.S. Republican, came close to reaching last year as Congress wrangled over raising the federal debt limit. Both parties have talked about trying to achieve around $4 trillion in deficit reduction over 10 years.
Their elusive "grand bargain," which ultimately unraveled, would have included Democrats agreeing to cuts in entitlement programs, such as Medicare and Medicaid, in exchange for Republicans signing off on new tax revenues.
Republicans have vowed to oppose any increase in tax rates, while Obama has demanded that tax rates on income above $250,000 snap back to higher levels. Some Republicans have expressed willingness to allow increased revenues as part of tax reform by eliminating some tax credits and deductions, but these have not been identified, and they want to reduce tax rates even further.
"This thing has been litigated in Washington for two years," one of the Democratic aides said.
"The reason a compromise has been tough to come by is because Republicans have been holding back, hoping to take the Senate and the White House" on Election Day, the aide said.
On Monday, it was unclear if Obama or Romney would win the White House, with polls in a statistical dead heat. But the polls indicated an increasing likelihood that Democrats would retain the Senate, which it now holds by a 53-47 margin.
Most political experts expect the House of Representatives to remain controlled by Republicans.
"The kind of compromises that are needed are pretty much known at this point," one aide said. "It is just a matter of political will."
"I think the message of the election - if it returns the president and a Democratic Senate and a Republican House - is that voters want both sides to work together," the aide said.
"Republicans would be seen as not heeding the message of the election if they continue to refuse to compromise," one aide said.
Boehner did little to fuel hopes for such a middle-ground on Monday, reiterating his vow not to raise taxes on the wealthy and arguing that this would hurt job creation.
"Listen, our (House) majority is going to get reelected," Boehner said in an interview with Politico. "We'll have as much of a mandate as he will - if that happens - to not raise taxes."
Democrats and Republicans have until the end of December to reach a massive deficit reduction deal or see the expiration of all tax cuts enacted under former president George W. Bush for millions of Americans, both the rich and middle class.
In addition, $1.2 trillion in spending cuts would begin to kick in, delivering a blow to the economy that experts predict would lead to a recession.
The Senate Democratic aides said the administration opposes calls for a short-term fix, which would renew all tax cuts for six months or so while a comprehensive agreement is sought. "The White House is showing no sign of caving on this," an aide said.