Treasury Secretary Timothy Geithner is warning Congress that Europe's debt crisis and a looming budget crisis in Washington could weaken an already-fragile U.S. economy.

Geithner also tells a House panel that regulators must pursue stricter oversight of the financial system to help stabilize the economy.

Geithner is expected to be questioned about his actions regarding banks' setting of a key global interest rate. Geithner, who was then president of the New York Federal Reserve, urged the Bank of England in 2008 to make the process for setting London interbank offer rate (Libor) rate more transparent. But he didn't make his concerns public.