Elizabeth Birnbaum

WASHINGTON (AP) -- The head of the troubled U.S. agency that oversees offshore drilling resigned under pressure Thursday as President Barack Obama moved more aggressively to take charge of the Gulf oil spill.
The departure of Minerals Management Service Director Elizabeth Birnbaum was announced by Interior Secretary Ken Salazar at a congressional hearing where Birnbaum had been scheduled to testify but didn't show up.
Birnbaum resigned "on her own terms and her own volition,'' Salazar told lawmakers.
The development came just hours before Obama was set to announce strong new measures in response to the spill, including extending a moratorium on new deepwater oil drilling and canceling some planned lease sales entirely. The midday White House event was to be Obama's first news conference since the Gulf of Mexico well began spewing oil.
Birnbaum, who had led MMS since July 2009, left after she and her agency came under withering criticism from lawmakers of both parties over allegedly lax oversight of drilling and cozy ties with industry. Salazar recently announced he was radically restructuring the agency into three separate parts.
In a three-sentence resignation letter to Salazar, Birnbaum wrote: "As you move forward with the reorganization of Minerals Management Service you will be requiring three new leaders ... I wish you every good fortune in the reorganization of the bureau.''
In the wake of an Inspector General's report alleging corruption at her agency during the previous administration, and indications that problems extended into the current one, Birnbaum's departure didn't satisfy some lawmakers.
"The departure of Elizabeth Birnbaum from MMS does not address the root problem. She has only been the public face of MMS for 11 months and the most serious allegations occurred prior to her tenure,'' said Rep. Nick Rahall, a Democrat and chairman of the House Natural Resources Committee.
"This might on the surface be a good start but must not be the end game,'' Rahall said.
It was a day of fast-moving developments in Washington and in the Gulf, where engineers were watching for signs of success from the latest attempt to stanch the leak five weeks into the catastrophe. The so-called "top kill'' technique of pumping heavy materials onto the leak appeared to make progress. At the same time, new estimates released by a team of scientists showed the spill has surpassed the Exxon Valdez as the worst in U.S. history, growing to nearly 19 million gallons (72 million liters) according to the most conservative estimate.
Obama planned to announce that a moratorium on new deepwater oil drilling permits will be continued for six months while a presidential commission investigates the disaster, a White House aide said.
Controversial lease sales off the coast of Alaska will be delayed pending the results of the commission's investigation, and lease sales planned in the Western Gulf and off the coast of Virginia will be canceled, the aide said, speaking on condition of anonymity ahead of Obama's news conference.
Those steps, along with new oversight and safety standards also to be announced, are the result of a 30-day safety review of offshore drilling conducted by Salazar at Obama's direction. Salazar briefed Obama on its conclusions Wednesday night.
The new announcements signaled a fundamental shift in the administration's policies on offshore drilling, which Obama promoted and hoped to expand prior to the spill. It was just in March that Obama announced a new policy on offshore drilling, throwing open a huge swath of East Coast waters and other protected areas in Alaska and the Gulf of Mexico to drilling. That expansion now looks like it will be dramatically rolled back for some time to come.
Obama will travel to the Gulf Coast on Friday, his second visit since the accident.