Obama Aide: Leak Is Biggest Environmental Disaster

President Barack Obama's top energy adviser says the Gulf oil spill is probably the biggest environmental disaster the country has ever faced.

And Carol Browner says the government is responding with what she calls its largest environmental response ever.

Already it's been called the biggest oil spill in U.S. history.

Browner says more oil is leaking into the Gulf of Mexico than from any previous U.S. oil spill — including the Exxon Valdez spill off the coast of Alaska in 1989.

Government estimates say that between 18 million and 40 million gallons have been dumped into the Gulf.

Browner spoke on NBC's "Meet the Press."