In Washington, environmental disasters come with a silver lining. They have the power to change the legislative dynamic almost overnight. A 1969 oil spill off the coast of Santa Barbara was the impetus for the original Earth Day, and prompted Congress to pass the National Environmental Policy Act, which among other things banned new offshore drilling. The Exxon Valdez oil spill in 1989 helped speed passage of the 1990 Clean Air Act Amendments, a landmark environmental law that Congress had been fighting over for eight years.

Historically speaking, then, a disaster like the one unfolding in the Gulf of Mexico would seem tailor-made to jump start a legislative process that has broken down amid partisan recriminations. And that certainly describes Washington. For months, a group of senators -- Democrat John Kerry, Republican Lindsey Graham, and Independent Joe Lieberman -- worked to craft an energy and climate bill that fell apart last week before it could even be introduced. Then came the Deepwater Horizon oil rig collapse. This should have prompted the Senate to look anew at the energy bill, which steers the country toward a cleaner, safer energy future.

But that's not what has happened. Many early responders in both parties have defended, not condemned, offshore drilling.

"I don't think that there's any argument that we should just start shutting down activity now, or even start shutting down new activity that's planned,'' Republican Senator David Vitter of Louisiana said on Sunday. House minority leader John Boehner seemed somehow encouraged. "This tragedy should remind us that America needs a real, comprehensive energy plan, like Republicans' 'all-of-the-above' strategy,'' he said Monday. The president's own response was the most feckless. "Let me be clear,'' President Obama intoned in a speech last week. "I continue to believe that domestic oil production is an important part of our overall strategy for energy security.''

The last month has seen two conspicuous energy failures related to the production of fossil fuels -- the deaths of 11 oil workers in the Gulf explosion, and the 29 miners in West Virginia who perished in the worst mine collapse in 40 years. It's also seen a major clean energy success in the approval of the Cape Wind project. A president more committed to clean energy would use these examples to press his case. Obama hasn't. He seems curiously reluctant to point out the obvious: The environmental dangers of over-reliance on fossil fuels.

This reluctance is grounded in political calculation. The Kerry-Graham-Lieberman bill, though much weaker than the climate bill that passed the House last summer, is widely viewed as the last, best shot at getting energy legislation to the president's desk during this Congress. It seeks to balance liberal and conservative interests by expanding support for nuclear power and offshore drilling, while imposing a price on carbon through a cap-and-trade scheme for electric utilities (gradually expanded to other industries) and a fee on oil, which would help spur the development of clean energy technology. Obama signaled his support for such a plan in his State of the Union address when he touted nuclear power and offshore drilling, while calling on Congress to "finally make clean energy the profitable kind of energy."

In the wake of the Gulf oil spill, the benefits of clean sources of energy are clearer than ever. What's so infuriating about the Washington response so far is that there's no indication the disaster has prompted Obama or anyone else to reconsider his position. In the past, major disasters shifted the terms of debate. This time, nobody is budging. But the support for offshore drilling that the White House was willing to trade for reductions in carbon emissions -- the crucial achievement in any climate bill -- is no longer feasible. As Florida Senator Bill Nelson put it, any bill that includes drilling is "dead on arrival.''

Perversely, the Gulf disaster has had the short-term effect of weakening the already tepid support for a Senate climate bill. That may change as Louisiana's coastline is subsumed by oil. Washington eventually responds to public outrage. (Just ask Goldman Sachs.) But for now, energy can join the long list of issues on which Washington leadership has vanished.

Senior editor Joshua Green writes a weekly political column for the Boston Globe.