WASHINGTON (Reuters) – President Barack Obama unveiled his much-anticipated plan on Wednesday to fight the U.S. housing crisis, pledging up to $275 billion to help stem a wave of foreclosures sweeping the country.

"All of us are paying a price for this home mortgage crisis. And all of us will pay an even steeper price if we allow this crisis to deepen - a crisis which is unraveling homeownership, the middle class, and the American Dream itself," Obama said in prepared remarks released on Wednesday.

Obama, who on Tuesday signed a landmark $787 billion economic stimulus bill aimed at jolting the U.S. economy out of recession, was to formally unveil his housing plan at 12:15 p.m. EST in Mesa, Arizona.

The U.S. housing crisis has played a central role in the financial and credit turmoil now spread across the globe, with many U.S. homeowners saddled with mortgages they cannot pay.

At the end of last year, just over 9 percent of all home loans in the United States were in arrears or already in foreclosure, the Mortgage Bankers Association has said.

A total of 8.1 million U.S. homes, or 16 percent of all households with mortgages, could fall into foreclosure by 2012, according to a report by Credit Suisse.

An Obama administration official said the total plan commits up to $275 billion for housing, including $50 billion from funds already committed in the country's financial sector bailout. It aims to help up to 9 million American families.

Mindful of critics who might charge that the scheme would help people who just took on far more debt than they could afford, Obama said his plan was aimed at "rescuing families who have played by the rules and acted responsibly," refinancing traditional mortgages for up 5 million homeowners who now are close to owing more than their homes are worth.

It will also establish a $75 billion fund to reduce monthly payments for another 3 million to 4 million homeowners "stuck in sub-prime mortgages they can't afford as a result of skyrocketing interest rates or personal misfortune," Obama said.

The Obama administration's summary of the plan said the plan could offer a buffer of up to $6,000 against value declines on the average home.

AIMS TO HEAD OFF WORSE PROBLEMS

The plan also aims to increase confidence in mortgage giants Fannie Mae and Freddie Mac through Treasury funding to "ensure the strength and security of the mortgage market and to help maintain mortgage affordability," the plan summary said.

"This initiative is intended to reach millions of responsible homeowners who are struggling to afford their mortgage payments because of the current recession, yet cannot sell their homes because prices have fallen so significantly," the summary said.

"By making these investments in foreclosure-prevention today, we will save ourselves the costs of foreclosure tomorrow - costs borne not just by families with troubled loans, but by their neighbors and communities and by our economy as a whole," Obama said.

The Treasury Department will double its financial support for housing finance giants Fannie Mae and Freddie Mac to allow them to play a bigger role supporting housing.

The Treasury said it was increasing its preferred stock purchase agreements with the two government-controlled companies to $200 billion each from $100 billion.

It also said it was raising the limit on the size of the mortgage portfolios the two companies can hold by $50 billion to $900 billion each, along with a corresponding increase in their allowable debt outstanding.