WASHINGTON (Reuters) - The U.S. Senate's top budget overseers on Tuesday joined forces to tackle escalating costs of retirement and health care programs they say threaten to bankrupt the government, but they would wait until after next year's elections for recommendations to be made public.

"We're headed for a cliff," said Senate Budget Committee Chairman Kent Conrad, a North Dakota Democrat, citing a looming explosion in "baby boom" retirees who will automatically qualify for expensive federal benefits.

Members of the huge so-called baby boom generation were born roughly from 1946 to 1964.

Conrad and Sen. Judd Gregg of New Hampshire, the senior Budget Committee Republican, said they would push legislation this year establishing a bipartisan task force to look into reforms.

But hoping to avoid congressional and presidential campaign politics that could doom their efforts, the task force report would not be delivered until Dec. 9, 2008. National elections are a month earlier.

Aides to House Budget Committee Chairman John Spratt, a South Carolina Democrat, said they did not know whether he would support the initiative.

House Speaker Nancy Pelosi, a California Democrat, rejected the idea of creating a task force to make recommendations for reforming Social Security and Medicare.

"This can be done by the committees of jurisdiction in Congress; they have the experience, knowledge and authority for addressing issues that arise with entitlements," Pelosi said in a statement.

Gregg, comparing the nation's fiscal problem to Hurricane Katrina that hit southern states in 2005, said baby boomer demands for Social Security retirement benefits and Medicare and Medicaid health care "will start to hit in 2010 and reach full force in 2025."

Those senior citizens will create "a $62 trillion unfunded liability" for the U.S. government, Gregg said.

If approved by Congress, the 16-member task force would be made up of eight Democrats and eight Republicans, including two from the Bush administration. The group would be headed by Treasury Secretary Henry Paulson.

Its recommendations would be put on a fast-track for approval, with votes in the Senate and House of Representatives in early 2009. The new president would then have to decide whether to sign the reforms into law.

While supporters say they are willing to consider all remedies, tax increases and other new revenues would cause heartburn for Republicans and benefit cuts could be troubling to Democrats. President George W. Bush has advocated private investment accounts to fix Social Security, but that idea met stiff opposition from Democrats and never got off the ground.