Factbox: Key players in the debate on housing finance

(Reuters) - The Obama administration is set to unveil its proposal for an overhauled system of U.S. housing finance by the end of this month.

The administration's plan will just be a starting point. Congress is expected to debate the issue thoroughly before making changes to the current system, centered around ailing mortgage finance giants Fannie Mae and Freddie Mac.

Differing views on the merits of the current system among Republican and Democrats suggest the debate will be lively.

The following is a list of some of the key players in the debate:

U.S. Treasury Secretary Timothy Geithner:

Geithner, a former president of the New York Federal Reserve Bank, played a key role orchestrating bank bailouts during the financial crisis

He also was instrumental in the administration's push for sweeping Wall Street reforms last year, which did not address Fannie Mae and Freddie Mac. The mortgage finance companies have received more than $150 billion in direct taxpayer support since being placed in a government conservatorship in 2008.

At an event on the future of housing finance last August, Geithner sketched out some basic tenets of the administration's likely approach, but offered no details.

"It is not tenable to leave in place the system we have today. We will not support returning Fannie and Freddie to the role they played before conservatorship, where they fought to take market share from private competitors while enjoying the privilege of government support," he said.

"I believe there is a strong case to be made for a carefully designed guarantee in a reformed system with the objective of providing a measure of stability in access to mortgage finance even in future economic downturns."

Treasury Undersecretary Jeffrey Goldstein:

Goldstein is a former private equity executive tasked with being the administration's liaison to Wall Street. Goldstein has kept a low profile since taking office in 2010, though housing finance reform is expected to be a key component of his portfolio. In a July blog post on the White House website, Goldstein stressed "the vital importance" of the housing market to "our country's future," but steered clear of any specifics.

Federal Housing Administration Commissioner David Stevens:

Stevens is a former executive with Long and Foster, the largest independently held residential real estate company in the United States, and has worked in top positions at Wells Fargo and Freddie Mac. Stevens is credited with shoring up the finances of the FHA by hiring the agency's first chief risk officer and tightening lending standards. Loans backed by the FHA account for close to 20 percent of new mortgage originations. Stevens wants to reduce the FHA's role in the mortgage market from those elevated levels.

Treasury counselor Gene Sperling

Sperling is currently a counselor to Geithner, but is in the running to be named as President Barack Obama's chief White House economic adviser, a post he held in the 1990s under President Bill Clinton. Sperling is known as a capable coordinator for economic policy. He spent a significant amount of his time at Treasury on initiatives aimed at boosting small business lending, though the programs had limited success.

House Financial Services Committee Chairman Spencer Bachus:

The soft-spoken Alabama Republican is quite a change, in both style and substance, from his predecessor, the outspoken liberal Barney Frank. Bachus believes the United States needs to be weaned from its reliance on government funding of mortgages. "What we now have is an addiction to government funding of mortgages," Bachus told Reuters late last year. He has also said the two firms should be in "liquidation," not "conservatorship."

House Republican Conference Chairman Jeb Hensarling:

Hensarling, from Texas, is a conservative Republican who has been a vocal critic not only of Fannie Mae and Freddie Mac, but of any government support for the U.S. housing market. He holds the No. 4 Republican leadership post in the House of Representatives.

"Fannie and Freddie were not born of a competitive marketplace, but in a government laboratory. They were allowed to exploit their implicit government guarantee to take on enormous risks. These two entities expose the taxpayer to unlimited risk and will likely end up receiving the mother of all bailouts," Hensarling said in a statement on his website.

Rep. Scott Garrett, chairman of the House Financial Services subcommittee on capital markets and government-sponsored enterprises:

Garrett, a New Jersey conservative Republican, this year takes the helm of the subcommittee responsible for oversight of Fannie Mae and Freddie Mac. He wants to wind down the firms within two years, a more radical position than even many of his Republican colleagues hold.

Senate Banking Committee Chairman Tim Johnson:

The Democratic lawyer from bank-friendly South Dakota is more conservative than his predecessor, Christopher Dodd, who retired last year. Johnson underwent brain surgery in 2006 and came away healthy, but with impeded speech. He has recovered and was present through the all-night talks leading to passage of the Dodd-Frank revamp of Wall Street regulation. Johnson is expected to take a go-slow approach to Fannie Mae and Freddie Mac, holding a number of hearings to gain a thorough understanding of their complexity before putting forth any specific Senate proposals. Keywords: USA HOUSING/PLAYERS

Senate Banking Committee top Republican Richard Shelby:

Another conservative Republican, Shelby has been a vocal critic of Fannie Mae and Freddie Mac. Late last year, he blocked Obama's pick to be the regulator of the two government-sponsored enterprises. Shelby accused the nominee, North Carolina's commissioner of banks, Joseph Smith, of being a "tool" of the Obama administration who would throw government money at the mortgage market and send the bill to taxpayers.

Fannie, Freddie acting regulator Edward DeMarco:

DeMarco is a career civil servant who has been acting director of the Federal Housing Finance Agency since August 2009. He had been expected to be replaced by Smith, but with the nomination blocked, he could stay in the acting role for some time. DeMarco is very focused on limiting taxpayer losses from Fannie Mae and Freddie Mac and has the power to exert substantial influence over how the two firms conduct their business.

House Financial Services Committee top Democrat Barney Frank:

Frank, a key architect of the financial regulation law that bears his name, lost the gavel of the House Financial Services Committee when Republicans took control of the House. However, as the panel's top Democrat on the key House committee responsible for Fannie Mae and Freddie Mac, he is likely to still wield considerable influence. He is a key ally of the Obama administration.

Frank has said the GSEs should be "abolished" in "current form" and a new housing finance system should be created. At the same time, he has stressed the importance of developing a new system before shutting the two firms down. "You can't really tear down the old jail until you've built the new one," he has said. (Reporting by Corbett B. Daly; Editing by Leslie Adler)