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WASHINGTON, March 29 (Reuters) - U.S. Treasury Secretary Timothy Geithner said on Sunday the government has about $135 billion left for bank bailouts yet refused to say whether it will ask Congress for more this year.

"We have roughly $135 billion left of uncommitted resources. The rest is out the door," he said on ABC-TV's "This Week with George Stephanopoulos" program.

Geithner said that figure included "a very conservative judgment about how much money is likely to come back from banks that are strong enough not to need this capital now to get through a recession."

Congress approved $700 billion last fall for rescuing banks that had gotten into trouble when the U.S. housing boom crashed, but lawmakers and ordinary Americans are showing signs of becoming increasingly unhappy over the program.

On NBC television's "Meet the Press" program, Geithner said it was essential the government step in to ensure that banks clean up their balance sheets, as it is doing so by promoting the establishment of public-private partnerships to rid banks of soured assets.

"We have two choices: we can leave it as it is, hope banks will earn their way out of this process over time, and I am certain that will create the risk of a deeper, longer recession," Geithner said.

"The classic lesson of financial crises is governments wait too late and that means more damage to the economy, higher deficits in the future and greater cost to the taxpayer," he added. "We're not prepared to take that approach."

On the ABC program, Geithner would not specify whether he expects to ask Congress for more money this year, though he did not rule it out. "The important thing is we are going to work with the Congress to make sure we have the resources needed to do this right.

"We have substantial resources, we're going to use them quickly, as carefully as we can ... to get credit flowing again and we'll cross that bridge when we come to it in terms of whether we'll need additional resources," Geithner added.

He conceded that U.S. banks likely will need "large amounts of assistance" before the credit crisis is resolved and said it would be "a mistake" to think that they can earn their way out of the current downturn.

"To get through this, governments need to act. There's a great obligation and responsibility for government to act to solve these things," Geithner said. "The market will not solve this and the great risk for us is that we do too little, not that we do too much."

Geithner was making a lightning trip to Colombia on Sunday to speak to the annual meeting of the Inter-American Development Bank, adding his voice to calls for institutions such as the International Monetary Fund to help counter the impact on emerging economies of the global financial downturn.

He will travel to London with President Barack Obama to attend a one-day session on Thursday of the Group of 20 rich and emerging-market countries where a commitment for increased funding for the IMF is widely seen as likely to be agreed. (Reporting by Glenn Somerville, editing by Maureen Bavdek)

www.reuters.com/article/governmentFilingsNews/idUSN2930354120090329