President Obama vowed Tuesday in a prime-time address that the oil would be cleaned up and the Gulf's ecology restored, and that oil company BP would compensate victims fully.

WASHINGTON — Calling the widening oil spill in the Gulf of Mexico “the worst environmental disaster America has ever faced,” President Obama vowed Tuesday in a prime-time address that the oil would be cleaned up and the Gulf’s ecology restored, and that oil company BP would compensate victims fully.

“We will fight this spill with everything we’ve got for as long it takes,” Obama said. “We will make BP pay for the damage their company has caused. And we will do whatever’s necessary to help the Gulf Coast and its people recover from this tragedy.”

The president also urged the nation to “tackle our addiction to fossil fuels,” prevailing upon Congress to pass a comprehensive bill that would embrace alternative sources of energy.

He said he would not tolerate inaction.

“The one answer I will not settle for is the idea that this challenge is too big and too difficult to meet,” Obama said. “You see, the same thing was said about our ability to produce enough planes and tanks in World War II. The same thing was said about our ability to harness the science and technology to land a man safely on the surface of the moon. And yet, time and again, we have refused to settle for the paltry limits of conventional wisdom.”

Before the address, congressional Republican leaders had warned the president not to use the Gulf spill to further his political agenda. And beyond the urgency of his appeal, his remarks largely were an 18-minute compilation of what he has said about the spill over the past several weeks.

The speech — the first of Obama’s presidency delivered from the Oval Office — came as the government increased its estimates of oil flowing from a pipe a mile deep in the Gulf, saying as much as 2.52 million gallons a day could be leaking into the ocean, and as BP continued its efforts to stem the spread of the 8-week-old spill.

The president vowed that the administration and BP would clean up “90 percent” of the oil before the end of the summer. But he also spoke of damage to the Gulf region that would linger for years.

Senior administration officials said Obama’s address — which they described as coming at an “inflection point” in the crisis — will help adjust the nation’s focus from the immediate spill to a longer-term strategy for restoring the Gulf region and changing the way the country uses energy.

The president’s address also was a bid to reverse sinking public approval of his administration’s efforts to respond to the disaster. Privately, one senior official said the speech was a direct effort to “wipe the slate clean,” adding the goal now is to “shift the conversation to something more future-oriented.”

To that end, Obama outlined a long-term plan to restore the “unique beauty and bounty” of the Gulf Coast wetlands and habitats, battered by decades of erosion, hurricanes and saline infiltration. He said Navy Secretary Ray Mabus, a former Mississippi governor, would develop the plan, working with local officials, fishermen and conservationists.

Obama offered an unswerving defense of his administration’s actions after the Deepwater Horizon rig exploded April 20. “Because of our efforts,” he said, “millions of gallons of oil have already been removed from the water.”

Even as the president spoke of BP’s “recklessness,” he avoided a lengthy, pointed critique of the company’s actions before and since the accident. Members of Congress — many of whom are worried about voter skepticism about the government’s effectiveness — have been less reticent, alleging BP ignored safety concerns in favor of cost-cutting measures.

The speech was not delivered with Obama’s trademark evenhanded efficiency, likely to assuage critics who have charged he has failed to display enough anger over the scope of the disaster.

Obama pledged to make Gulf Coast residents and businesses whole, and said a BP-funded compensation account would be set up and administrated by an independent third party. All legitimate claims, he said, would be paid in a “fair and timely manner.”

The president will meet with BP executives at the White House on Wednesday to discuss the fund, which could run into the billions.

Obama also called on Congress to pass a comprehensive energy bill without going so far as to endorse limits on carbon emissions. Disagreement over such limits has stalled such a bill in the Senate.

“For decades, we have known that the days of cheap and easily accessible oil were numbered,” Obama said. “And for decades we have failed to act with the sense of urgency that this challenge requires.”

Before returning to the White House for the speech, Obama wrapped up his fourth visit to the Gulf since the explosion, touring Alabama, Mississippi and Florida over two days, meeting with local officials and speaking to small-business owners.

Information from The Washington Post is included in this report.