Geithner was responding to questions from Sen. Susan CollinsSusan CollinsGOP healthcare plans push health savings account expansion A guide to the committees: Senate Pruitt sworn in as EPA chief MORE (R-Maine) over why the administration hadn't sought to fix problems with the government-sponsored mortgage giants in the financial regulation reform bill the Senate is now debating.
"It concerns me that we've yet to tackle these [government-sponsored enterprises]," Collins said. "They've played a critical role in the collapse of the economy. I don't know what we're waiting for."
Critics of Fannie and Freddie said those firms were too willing to lend home loans to people who couldn't afford them, helping build the real estate market bubble.
Geithner said it was better to take complex regulatory reforms in stages instead of all at once.
"We thought it was best to the important and difficult task of reforming the housing market to a second stage," he said.
He added that the administration is committed to pushing Fannie and Freddie reforms soon.
"We're more likely to get it right if we go thru a careful process," he said.