The head of the Interior Department's embattled oil and gas drilling program announced Monday he is retiring at the end of the month, a move that comes as the agency he runs faces a shake-up following the BP oil spill in the Gulf of Mexico.

Chris Oynes, the associated director of the Offshore Energy and Minerals Management Program within the Mineral Management Service at the Interior Department, announced his departure in an e-mail to his staff.

President Obama, meanwhile, has decided to have a presidential commission investigate the cause of the rig explosion that unleashed millions of barrels of oil into the Gulf of Mexico, where engineers are struggling after three weeks to stop the flow.

The presidential panel will be similar to ones that examined the Challenger space shuttle disaster and Three Mile Island nuclear power plant accident, said a White House official, speaking on condition of anonymity because the decision had not been formally announced.

Oynes is responsible for the Outer Continental Shelf oil and gas program, as well as developing and implementing the new alternative energy program. 

Oynes' biography on the Mineral Manager Service's website notes that he has been involved in how the agency conducts its resource projections, environmental reviews and operational safeguards. He also was directly responsible for 30 lease sales.

The agency specifically has been accused of being too cozy with the oil and gas lessees it oversees.

In Congress, more attention was focused on the Gulf spill. Sen. Barbara Boxer, D-Calif., and seven other senators asked the Justice Department to determine whether BP PLC made false and misleading claims to the government about its ability to prevent a serious oil spill when it applied for permission last year to drill the Deepwater Horizon well that has unleashed environmental havoc along the Gulf coast.

But lawmakers are taking aim not only at BP at hearings this week, but also the Interior Department's regulation of offshore drilling that allowed BP to operate without assurance a massive spill could be prevented.

Anticipating tough questioning on Capitol Hill at hearings this week, Interior Secretary Ken Salazar on Monday announced a tightening of requirements for onshore oil and gas drilling. The new measures would not apply to oil rigs at sea.

"The BP oil spill is a stark reminder of how we must continue to push ahead with the reforms we have been working on and which we know are needed," Salazar said.

Oynes is the first person to resign at his agency since an April 20 explosion at the Deepwater Horizon oil rig sunk the rig and caused the massive oil spill. The spill continues to grow as oil officials and federal authorities race to stop the flow and protect the coast.

Rep. Darrell Issa, R-Calif., ranking member of the House Oversight and Government Reform Committee, issued a statement saying that Oynes' departure is a start.

"For more than a decade spanning three administrations, MMS has been a corrupt agency with an extensive history of mismanagement. This wasn't the doing of one, single person, but rather the culmination of a bureaucratic breakdown. Removing one person might be a start, but MMS is in need of an exhaustive overhaul and comprehensive reform," Issa said.

Fox News' Major Garrett and The Associated Press contributed to this report.