WASHINGTON  The Obama administration and the Federal Reserve, still smarting from the political furor over the bailout of American International Group, began a full-court press on Tuesday to expand the federal government’s power to seize control of troubled financial institutions deemed too big to fail.

In his news conference on Tuesday night, President Obama said the government could have handled the A.I.G. bailout much more effectively if it had had the same power to seize large financial companies as it did to take over failed banks.

“It is precisely because of the lack of this authority that the A.I.G. situation has gotten worse,” Mr. Obama said, predicting that “there is going to be strong support from the American people and from Congress to provide that authority.”

Earlier on Tuesday, the Treasury secretary, Timothy F. Geithner, offered a proposal that would allow the government to take control, restructure and possibly close any kind of financial institution that was in trouble and big enough to destabilize the broader financial system.