President George W. Bush signed a bill Wednesday aimed at boosting the American economy by shoring up the housing market and instituting mortgage lending reforms.

The bill includes $300 billion to allow homeowners in danger of foreclosure to refinance their mortgages and expands oversight of Fannie Mae and Freddie Mac, the two U.S. government-chartered institutions that back almost half of the estimated $12 trillion of mortgage debt in the country.

It includes a $7,500 first-time buyer tax credit for houses bought between April 9, 2008, and July 9, 2009.

The National Association of Home Builders, which had long been pushing for the legislation, heralded its becoming a law.

“This milestone bill contains several provisions to get home buyers back into the marketplace, stop the slide in home prices, provide a lifeline to borrowers facing foreclosure, improve mortgage liquidity and bolster confidence in Fannie Mae and Freddie Mac," said association President Sandy Dunn of Point Pleasant, W.Va. "We commend Congress and the president for taking this action to provide much-needed relief to the American people.”

Dunn was especially excited about the $7,500 credit available as part of the new law.

"The tax credit is the best stimulative measure," she said. “It will increase housing demand, get home buyers back into the marketplace and fight falling home prices, which threaten the economy as a whole.”

Bush initially opposed the measure as too anti-free market and threatened a veto. But widespread support in Congress and among some member of his cabinet, along with stricter oversight of Fannie Mae and Freddie Mac, convinced the president to sign the measure.

“We look forward to put in place new authorities to improve confidence and stability in markets and to provide better oversight for Fannie Mae and Freddie Mac,” said White House spokesman Tony Fratto. “The Federal Housing Administration will begin to implement new policies intended to keep more deserving American families in their homes.