The Obama administration is starting a criminal and civil investigation into the BP oil spill, including possible violations of a range of environmental and safety laws.
The probe, announced by Attorney General Eric Holder, is among a series of key steps the White House is taking as it tries to recover from a slow and muted initial response to the disaster.
"Obviously this has gone on far too long," press secretary Robert Gibbs said at the White House.
Starting immediately, the Coast Guard will no longer conduct briefings on the oil spill in company with officials from BP -- a move both symbolic and substantive reflecting the government's frustration with the oil giant's conduct.
The president, showcasing a steely resolve missing from last week's press conference on the disaster, appeared in the Rose Garden to announce the formation of a new commission to investigate the spill.
"We owe all those who've been harmed, as well as future generations, a full and vigorous accounting of the events that led to what has now become the worst oil spill in U.S. history," Obama said.
Severing ties with BP has becoming an urgent matter for the White House, which earlier depicted the disaster response following the April 20 incident as a partnership.
Obama later conceded the government was forced to depend in part on BP's superior equipment and technology in managing the response. But with the oil giant's safety record and veracity increasingly in question and now under investigation, the administration is distancing itself.
Also of concern is the start of hurricane season, and the effect any major storm systems could have on efforts to contain and manage the devastating spill. BP has said it could take until August to halt the flow of oil and gas into the Gulf of Mexico.
After last week's efforts to plug the underwater gusher failed, the oil company said it will send robots underwater to cut the pipe and install a cap.
Obama returned to work Tuesday after a long weekend at home in Chicago. While he was away, pundits, columnists and politicians from both parties pummeled him for what many called a detached, passionless response to the disaster.
When Marine One landed on the South Lawn of the White House Monday night, the president walked directly into the Oval Office. Gibbs later described Obama as angry.
"I've seen rage from him. I have," Gibbs said. "He has been in a whole bunch of different meetings -- clenched jaw, even in the midst of these briefings, saying everything has to be done -- I think this was an anecdote shared last week -- 'to plug the damn hole.'"
Whether the administration's attitude adjustment and breakup with BP improve their public relations remains an open question. A new Quinnipiac Poll found 42 percent disapprove of Obama's handling of the spill, to 39 percent who approve.
BP's troubles, meanwhile, continue to multiply. The energy giant on Tuesday lost millions in stock value in the wake of the latest failed attempt to contain the oil spill.