Treasury Secretary Timothy Geithner asked lawmakers Tuesday to pass legislation on Fannie Mae and Freddie Mac reform within the next two years. In February, the Treasury Department released its much anticipated white paper on the future of housing finance. The proposal suggested three options for Congress to break up the government-sponsored enterprises and reduce the government's role in the market. The options range from a completely privatized market to one with some crisis or insurance fund paid for by the private companies that take over Fannie and Freddie's role in the market. "Each of the longer-term reform options we have outlined will require legislation from Congress, and we hope to work together with you and your colleagues to pass comprehensive legislation within the next two years," Geithner said in his testimony. "Failing to act would exacerbate market uncertainty and risk leaving many of the flaws in the market that brought us to this point in the first place unaddressed. While Geithner suggested a two-year time frame for legislation to be passed, he warned the House Financial Services Committee that decision makers should take careful consideration when determining how fast the wind down is done. "I want to emphasize that it is very important that we wind down Fannie Mae and Freddie Mac at a careful and deliberate pace. Closing the doors at Fannie Mae and Freddie Mac without consideration for the pace of economic recovery could shock an already fragile housing market, severely constrain mortgage credit for American families, and expose taxpayers to unnecessary losses on loans the institutions already guarantee," Geithner said. Opinions vary wildly on when reform will actually begin. Rep. Barney Frank (D-Mass.) told Bloomberg Television just before the white paper was released that a deal could be reached by the end of the year. Banking analysts at the Royal Bank of Scotland, however, don't see changes coming for another 15 years. Once Congress does decide which option to choose, the Treasury Department anticipates the process to take between five and seven years. "While we are confident that the steps we have laid out follow the right path, haste would be counterproductive – possibly destabilizing the housing finance market or even disrupting the broader recovery," Geithner said. Write to Jon Prior. Follow him on Twitter: @JonAPrior