Published: Apr 29, 2010 7:49 PM EDT

WASHINGTON - President Barack Obama pledged an all-out response Thursday to the massive oil spill now expected to reach the Gulf Coast within a day and dispatched top officials to the region to help coordinate defenses against the potential environmental disaster.

At the White House, Coast Guard Rear Adm. Sally Brice-O'Hara said, "We are being very aggressive and we are prepared for the worst case." Federal officials announced inspections would begin immediately of all oil rigs in the Gulf and subpoena powers would be used in the gathering investigation. But the priority was to support the oil company BP PLC in employing booms, skimmers, chemical dispersants and controlled burns to fight the oil surging from the seabed.

The administration rejected suggestions that the federal government was slow to act in dealing with the spill and expressed frustration with BP's inability to seal the ruptured well head. The government approved the start of drilling for a relief well and was considering approving a second one as industry and government officials worked on multiple fronts to contain the slick.

Obama promised to deploy "every single available resource" to the area and ordered his disaster and environmental leaders to go. The Navy is sending 66,000 feet of inflatable boom and seven skimming systems, and using its bases in the region as staging areas for the operation.

Brice-O'Hara said officials expected the leading edge of the spill to reach the Mississippi Delta sometime on Friday. Workers were racing from six staging areas to deploy more booms to try to hold off the slick and protect sea life and fragile wetlands.

Winds and sea conditions Thursday prevented another controlled burn of the kind tried successfully a day earlier with a small test section of the slick.

Top Homeland Security, Interior and Environmental Protection Agency officials were going to the region. Officials emphasized at a White House briefing that all costs of the defense and recovery will ultimately fall on the industry, not taxpayers. Obama spoke Thursday with five Gulf state governors from Florida to Texas.

The administration declared the spill to be one of national significance, a designation that eases the transfer of personnel and equipment to the region from all parts of the country. Michael Sole, chief of Florida's Environmental Protection Department, said governments are digging in for a long struggle and it's too soon to know what his state will need from Washington.

"It's only been a week now," he said. "It may be two or three months before they can stop the discharge. The magnitude of this thing gives me concerns as to whether they're going to be able to address the entire coast of the Gulf of Mexico."

So far, he said, the federal government has acted aggressively and cooperatively.

Navy sends equipment to help with Gulf oil spill

The Navy sent equipment to help with cleanup of the Gulf of Mexico oil spill and the Pentagon said Thursday it stands ready to expand its response to the disaster.

Navy spokesman Lt. Myers Vasquez said Thursday that 66,000 feet of inflatable boom and seven skimming systems were on their way to the Navy base in Gulfport, Miss. The help is being provided under an existing pollution cleanup agreement between the Navy and Coast Guard.

The Pensacola Naval Air Station in Florida is in use as a staging area for more booms, recovery barges, tractor trailers, pumps and other related equipment used by Coast Guard contractors, Vasquez said. He was unaware of any military personnel who might be sent to help with the cleanup.

The White House has asked the Defense Department to discuss possible additional requests. Pentagon press secretary Geoff Morrell said the military is assessing how it might help and what resources could be deployed. He did not say how long that might take.

"There is a full-blown effort within this department to try to find the kinds of things that could be helpful," Morrell said. He said the federal response is far wider than the Pentagon and should involve a close partnership with the energy industry.

For example, he said, industrial research on submersible vehicles that can operate at great depth outpaces the military's. Morrell said the focus of military efforts now is on helping to contain the spill at sea, but that the Pentagon would be ready to offer other kinds of help should the spill reach shore.

He would not speculate on what that additional assistance might include, but one possibility would be an influx of U.S. troops to help with shoreline cleanup.