Like those oil-besmirched pelicans thrashing about in misery in the Gulf of Mexico, President Obama finds himself now politically engulfed in the worst environmental disaster in American history.

WASHINGTON — Like those oil-besmirched pelicans thrashing about in misery in the Gulf of Mexico, President Obama finds himself now politically engulfed in the worst environmental disaster in American history.

The gigantic British Petroleum oil spill has compromised his ability to deal with all the other serious challenges of his presidency, obliging him once again to postpone his long-planned trip to Australia and South Asia.

A third trip to the Gulf Coast in a month surveying the damage has served mainly to underscore the limits of the power of the presidency in coping with such a national calamity. The fact that it was not of his making is giving him little slack now as he essentially and unavoidably has accepted it as his own nightmare.

Like it or not, those images on the nation's television screens and newspaper front pages of the oil-sopped pelicans are an unhappy metaphor for Obama himself. He is taking the political fall specifically for BP and by extension for past failures to regulate adequately the oil industry's safeguards against such a catastrophe.

No amount of castigating BP and restating its full financial responsibility for the cost of cleaning up the mess can mitigate the truism of the sign that once graced the Oval Office desk of President Harry Truman: "The Buck Stops Here." Obama himself resignedly expressed the sentiment the other day as the November congressional elections approach, and his own reelection hopes in 2012.

In his fashion, the famously cool-headed president, while saying in a CNN interview he was "furious at the entire situation," added he could not waste his time "venting and yelling at people," and that "ultimately this isn't about me and how angry I am."

Even as BP's hapless CEO, Tony Hayward, whines concerning the ordeal that "I'd like to have my life back," the giant oil corporation's public-relations wizards have begun spending a small fortune running a slick television mea-culpa commercial. It features Hayward's apology for the suffering imposed and again pledging restitution.

Meanwhile, the oil spill is despoiling whatever good news manages to ooze into public consciousness. As economic indicators continue to demonstrate small but steady progress toward recovery from the recession, such as Friday's announcement of 431,000 more new jobs created and a drop in the unemployment rate to 9.7 percent, little cheering is heard.

Bad news for the administration, however, still manages to generate news media attention despite the mesmerizing oil-spill saga. It has failed, for example, to cover up the business-as-usual White House practice of seeking to affect the outcome of elections by real or just suggested job offers.

On the heels of the acknowledgment that former President Bill Clinton was asked to discourage Rep. Joe Sestak from challenging Sen. Arlen Specter's reelection, which failed, other allegations have surfaced. A Democratic challenger to incumbent Democratic Sen. Michael Bennett in Colorado has said similar White House pressures failed to drive him off, while admitting no firm offers had been made.

This sort of political arm-twisting has been commonplace in Republican and Democratic administrations alike for years. But Obama's repeated boast of planning to change the way Washington works has particularly engendered unfavorable commentary.

Taken together with the continuing drumbeat of obstruction from the Republican congressional leadership toward most of the Obama domestic agenda now engulfed in the oil-spill calamity, the president is increasingly struggling to regain the political initiative.

All new presidents, to be sure, soon find that the unpredictability of events have complicated their best-laid plans for reshaping the country to their visions because "the buck stops" at their Oval Office desk. For Obama's predecessor, the 9/11 terrorist attacks indisputably made the point.

It could be argued that George W. Bush had no easily discernible agenda in place, and that therefore the segue to a wartime presidency was both necessary and convenient. But Obama laid out grandiose plans for his White House, which the Gulf oil spill has seriously imperiled, along with his own political future.

In any event, he has no option but to press on with the effort to cap the well, in a way that demonstrates a more certain leadership hand than he has been able to exhibit under trying circumstances so far.

Jules Witcover's latest book, on the Nixon-Agnew relationship, "Very Strange Bedfellows," has just been published by Public Affairs Press. You can respond to this column at juleswitcover@comcast.net.