The government has plowed $188 billion into Fannie and Freddie. By the end of September, the companies will have sent $146 billion in dividends back to the Treasury with nearly two-thirds of those payments made this year. Many analysts forecast that within a year, the firms will have sent more to the Treasury than they borrowed.

Fannie and Freddie are reporting banner profits thanks to rising home prices and falling mortgage delinquencies. They have boosted the fees they charge lenders while refusing to guarantee risky loans. Private investors have shied away from buying mortgages without federal backing, leaving Fannie, Freddie and other federal agencies responsible for insuring nearly 90% of all loans.

As the debate over the companies' future comes to a head, policy makers' views of the causes of the 2008 crisis have shaped their proposed solutions.

Some conservatives see Fannie and Freddie as the chief culprits of the bubble, saying that they pioneered risky lending standards at the urging of politicians who wanted to boost the homeownership rate. Rep. Jeb Hensarling, a Texas Republican who chairs the House Financial Services Committee, is moving forward a bill to wind down Fannie and Freddie over five years and cede their roles to the private sector.

Other lawmakers say Fannie and Freddie helped inflate the bubble but weren't necessarily the worst offenders. In their view, the companies ran off the rails because as shareholder-owned firms, executives couldn't resist the urge to buy riskier loans to grab extra profits even as the housing market overheated.