By Kara Rowland

Just weeks after he opened up new areas to offshore drilling, President Obama reversed course Thursday and suspended or canceled drilling projects in the Gulf of Mexico, the Atlantic and the Arctic, as promising signs emerged from BP’s latest effort to plug a gushing oil leak off the coast of Louisiana.

While taking responsibility for what critics have dubbed a haphazard response to the worse oil spill in U.S. history, Mr. Obama – without naming the Bush administration – pointed at his predecessor by blaming the Gulf disaster on “a scandalously close relationship between oil companies and the agency that regulates them.”

Mr. Obama said his administration has been trying to clean up that agency, the Minerals Management Service. MMS’ chief, Elizabeth Birnbaum, an Obama nominee, quit her post Thursday just before Mr. Obama held a press conference. Mr. Obama was not sure whether Ms. Birnbaum resigned or was asked to leave.

On Thursday, federal scientists said the leak, caused by an explosion on the Deepwater Horizon oil rig that killed 11 people last month, is thought to be spewing as much as 1 million gallons of oil a day – making it far worse than the Exxon Valdez spill in 1989.

The White House press corps put Mr. Obama on the defensive, repeatedly questioning the speed at which his administration has responded to the disaster and its oversight of BP’s efforts, which repeatedly have failed over the last five weeks. A frustrated public has voiced its disapproval of the administration’s efforts in recent polls.

Mr. Obama dismissed critics, saying they “don’t know the facts.” But he did say he’d leave it to others to judge when asked about comparisons to President George W. Bush’s oft-criticized response to Hurricane Katrina.

The president, who will visit the coast on Friday before heading to Chicago for the holiday weekend, said the spill serves as a “wake-up call” that the country must move past drilling and embrace a clean-energy economy, and he argued that despite his now-reversed overture to open up more drilling, he was never that fond of the idea.

“That’s part of the reason you never heard me say, ‘Drill, baby, drill,’ ” Mr. Obama told reporters in his first full-scale East Room press conference since July.

In response to a preliminary report on the spill by the Interior Department, Mr. Obama said he’s decided to suspend the planned exploration of two locations off the coast of Alaska and cancel lease sales for locations in the Gulf of Mexico and off the coast of Virginia. In addition, he ordered a six-month extension of an existing moratorium on issuing new permits to drill deep-water wells and suspended action on 33 exploratory deep-water wells currently being drilled in the Gulf.

The decision to stop oil exploration in the deep Gulf and in Alaska drew harsh rebuke from supporters of offshore drilling.

“I think putting our drilling programs in those areas in a deep freeze is exactly the wrong approach,” said Rep. Joe Barton, the senior Republican on the House energy panel. “All we’re going to do is cause unemployment and cause the price of oil to go up, which is going to hurt our economy even more.”

But environmental groups who opposed Mr. Obama’s initial announcement in April that he was opening up some new swaths of land for drilling while closing off others, praised the steps.

“The ongoing tragedy in the Gulf Coast clearly demonstrates that our dependence on oil – be it from hostile nations or friendly coasts – hurts our economy, threatens our security and harms our environment,” League of Conservation Voters President Gene Karpinski said.

Mr. Obama said that BP is “operating at our direction” as it tries to stop oil from spewing into the water, and assured Americans that he takes responsibility for the response to the crisis.

“In case you’re wondering who’s responsible, I take responsibility,” he said. “It is my job to make sure that everything is done to shut this down. That doesn’t mean it’s going to be easy. It doesn’t mean it’s going to happen right away or the way I’d like it to happen. It doesn’t mean that we’re not going to make mistakes. But there shouldn’t be any confusion here. The federal government is fully engaged, and I’m fully engaged.”

Judging by recent opinion polls, the public doesn’t seem to think anyone is doing a good job of handling the disaster. In a CNN/Opinion Research survey released Monday, 51 percent of Americans say they disapprove of the way President Obama is handling the crisis, though even more – 76 percent – say they disapprove of BP’s response to the spill.

Mr. Obama lauded Interior Secretary Ken Salazar for cleaning house at MMS but argued that more must be done to change a culture created by the Bush administration “in which oil companies were able to get what they wanted without sufficient oversight and regulation.” He cited as “appalling” a recent inspector general’s report that chronicled what he described as corruption at the agency, which Mr. Salazar announced will be split up to ensure its regulatory duties don’t conflict with its charge to collect royalties from oil companies.

Asked about Ms. Birnbaum’s departure, Mr. Obama said her resignation would have gone to Mr. Salazar – another Obama appointee and a friend from the Senate – with whom he had yet speak about the matter.

In April, Mr. Obama announced plans to expand drilling off the coast of the southern Atlantic seaboard, in the Gulf of Mexico and some parts of Alaska. At the same time, he ordered a halt to future sales in Alaska’s Chukchi and Beaufort seas that drilling advocates say could account for far more oil than the new areas he wanted to open up.