WASHINGTON (AP) — President Barack Obama gave the leaders of an independent commission investigating the Gulf oil spill marching orders Tuesday to thoroughly examine the disaster and its causes to ensure that the nation never faces such a catastrophe again. He said if any laws were broken, people will be prosecuted.

Obama spoke in the Rose Garden on Tuesday after meeting with the co-chairmen of the commission, Bob Graham, a former Florida governor and U.S. senator, and William K. Reilly, a former head of the Environmental Protection Agency,

“They have my full support to follow the facts wherever they lead, without fear or favor,” Obama said.

The president said that if laws are insufficient, they’ll be changed. He said that if government oversight wasn’t tough enough, that will change, too. And Obama said if laws were broken, those responsible will be brought to justice.

Obama directed the co-chairs to report back in six months “with options for how we can prevent and mitigate the impact of any future spills that result from offshore drilling.”

In a sign of an increasingly assertive administration role, Attorney General Eric Holder also planned to visit the Gulf Coast Tuesday to see areas affected by the oil spill and to meet with state attorneys general and U.S. prosecutors.

Several senators have asked the Justice Department to determine whether criminal or civil laws were broken in the spill. The Justice Department has told Sen. Barbara Boxer, who heads the Senate’s environment committee, that it has ordered BP PLC not to destroy documents that could be relevant in an investigation.

Holder was scheduled to receive a Coast Guard tour, then meet with the attorneys general of Louisiana, Alabama and Mississippi and several U.S. attorneys.

The independent commission’s inquiry will range from the causes of the spill to the safety of offshore oil drilling and the functioning of government agencies that oversee drilling.

Obama’s session with Graham and Reilly and Holder’s visit to the Gulf Coast come three days after BP said its latest attempt to stop the oil spewing out of a broken well 5,000 feet underwater had failed. Obama visited coastal Louisiana four days ago to assess the situation and assure residents frustrated by the government’s response that he is doing everything possible to fix the well.

WATCH MSNBC COVERAGE HERE:

Visit msnbc.com for breaking news, world news, and news about the economy

Amid concern that the worst oil spill in U.S. history could threaten his presidency, Obama has stepped up his public appearances to demonstrate that he is engaged. He held a White House news conference Thursday, focused almost entirely on the oil spill, and followed that with the Gulf visit on Friday.

Tuesday’s meeting was Obama’s first with the commission since he named it less than two weeks ago.

Obama still must name five members of the commission, which will investigate such issues as what caused the spill, the safety of offshore drilling and operations at the federal agency that grants drilling rights.

The Gulf oil spill began April 20 when BP’s Deepwater Horizon drilling rig exploded off the Louisiana coast, killing 11 workers and rupturing the underwater pipe.

In the six weeks since, the government estimates that between 19.7 million and 43 million gallons of crude have poured into the Gulf — affecting beaches, wildlife and the local economy and making it the worst spill in U.S. history.

After BP announced Saturday that its latest attempt to stop the oil, known as a “top kill,” had failed, Obama said that disappointing news was “as enraging as it is heartbreaking.”

It was the latest in a series of failed efforts by the British oil company to shut off the oil flow. BP will try again as early as Wednesday when it attempts to put a cap on the leaking well so oil can be siphoned to the surface.

Graham, a Democrat, served in the Senate from 1987 to 2005 and previously served two terms as Florida governor. Reilly served as EPA administrator under President George H.W. Bush.

Meanwhile, Carol Browner, a top adviser to Obama, said she doesn’t want to guess the prospects for success when BP again tries to use a containment cap to control the Gulf Coast oil spill.

Interviewed Tuesday on ABC’s “Good Morning America,” the White House energy and global warming czar said, “I don’t want to put odds on it. … We want to get this thing contained.”

Browner said “everyone, I think, is hoping for the best, but we continue to plan for the worst.” She said she’s concerned about the impact the hurricane season could have on ending the environmental crisis.

Copyright 2010 The Associated Press.