From Edward Pinto's Wall Street Journal op-ed:

Congress's goal was to force these two government-sponsored enterprises (GSEs) to purchase loans that had been originated by banks -- loans that were made under the pressure of another federal law, the 1977 Community Reinvestment Act (CRA), to increase lending in low- and moderate-income communities.

From 1977 to 1991, $9 billion in local CRA lending commitments had been announced. CRA lending by large banks increased dramatically after the affordable housing mandate was in place in 1993, growing to $6 trillion today. As Ellen Seidman, director of the federal Office of Thrift Supervision, said in a speech before the Greenlining Institute on Oct. 2, 2001, “Our record home ownership rate [increasing from 64.2% in 1994 to 68% in 2001], I'm convinced, would not have been reached without CRA and its close relative, the Fannie/Freddie requirements.”

The 1992 GSE Act was the fuse, and the trillions of dollars in subsequent CRA and GSE affordable-housing loans would fuel the greatest housing bubble our nation has ever seen. But who lit the fuse?

[...]

Fifty percent of the high-risk loans are estimated to be CRA loans, with much of the remainder useful to the GSEs in meeting their affordable-housing goals.

The flood of CRA and affordable-housing loans with loosened underwriting standards, combined with declining mortgage interest rates-to 5% in 2003 from 10% in early 1991-resulted in a massive increase in borrowing capacity and fueled a house price bubble of unprecedented magnitude over the period 1997-2006.

Now this history may repeat itself as many of the same community groups are pushing Congress to expand CRA to cover all mortgage lenders, credit unions, insurance companies and others financial industry segments. Are we about to set the stage for another catastrophe? [The Wall Street Journal, 11/13/09]

Myth that CRA and affordable housing initiatives caused crisis has been widely discredited

Bernanke: Experience “runs counter to the charge that CRA was at the root of, or otherwise contributed in any substantive way to, the current mortgage difficulties.” In a November 25, 2008, letter, Federal Reserve chairman Ben Bernanke stated: “Our own experience with CRA over more than 30 years and recent analysis of available data, including data on subprime loan performance, runs counter to the charge that CRA was at the root of, or otherwise contributed in any substantive way to, the current mortgage difficulties.”

SF Reserve Bank's Yellen: "[S]tudies have shown that the CRA has increased the volume of responsible lending to low- and moderate-income households." Janet Yellen, president and CEO of the Federal Reserve Bank of San Francisco, stated in a March 2008 speech that “studies have shown that the CRA has increased the volume of responsible lending to low- and moderate-income households.”