WASHINGTON (Reuters) - The Obama administration, in an election-year bid to help distressed homeowners, on Friday expanded its main foreclosure prevention program, and pushed for Fannie Mae and Freddie Mac to forgive mortgage debt. The administration said it would extend the life of the Home Affordable Mortgage Program by a year through 2013 and widen it to reach more heavily indebted homeowners. It also said it would provide incentives to encourage Fannie Mae and Freddie Mac, the government-controlled mortgage finance provider, to write down loans, an idea which their regulator has worried would unnecessarily add to the cost of taxpayer bailouts for the two firms. The regulator, the Federal Housing Finance Agency, withheld final judgment on the proposal, saying it would study it further. Fannie Mae and Freddie Mac own or guarantee about half of all U.S. home loans, and their participation in principal reduction under HAMP could greatly expand the reach of the $29.9 billion program. Nearly 11 million Americans are underwater on their mortgages - meaning they owe more than their homes are worth. With some key electoral swing states among the hardest hit by the housing crisis, the sector's health could become an important factor in November's elections. President Barack Obama made clear in his State of the Union address on Tuesday that he would continue to press for aggressive action to help homeowners, and Friday's announcement was just the first of several on housing initiatives that are expected in coming weeks. Republicans in the House of Representatives last year sought to shut down HAMP, arguing it was ineffective, but the bill died in the Democratic-led Senate. When the administration launched the program in 2009, it expected as many as 4 million loans would be modified. So far, only about 900,000 households have permanently won new loan terms. As of the end of last year, only about $3 billion had been spent of the $29 billion set aside for HAMP. As part of its effort to reach more Americans, both the Treasury Department and the Department of Housing and Urban Development said they would seek to aid homeowners pinched by other types of debt, including credit cards and medical bills. In addition, the administration said it was tripling the incentives paid to investors when they reduce loan balances. FHFA's acting director, Edward DeMarco, has argued that Fannie Mae and Freddie Mac could provide equal relief to homeowners through loan forbearance at less cost to taxpayers than slashing mortgage debt. Treasury has notified the FHFA that it "will pay principal reduction incentives to Fannie Mae or Freddie Mac if they allow servicers to forgive principal in conjunction with a HAMP modification," Treasury Assistant Secretary Timothy Massad said. By offering taxpayer money to cover the costs of write-downs at Fannie Mae and Freddie Mac, the Obama administration is seeking to overcome DeMarco's objections. "DeMarco said he is willing to reconsider principal reduction for mortgages backed by Fannie and Freddie, if, in his words, 'a source of funds outside the enterprises emerge to cover some portion of the costs associated with reducing principal,'" Senator Jack Reed, a member of the Senate Banking, Housing & Urban Affairs Committee, said in a statement. "The administration has now made those funds available," Reed, a Rhode Island Democrat, said. I expect FHFA to promptly reconsider their analysis and help more Americans avoid foreclosures. Reed has been urging the administration to tap HAMP for principal reductions on loans backed by Fannie Mae and Freddie Mac. Reporting By Margaret Chadbourn; Editing by Andrea Ricci, Tim Ahmann, Andrew Hay, Leslie Adler