WASHINGTON - Charts at the ready, notes spread out before him, Rep. Roscoe G. Bartlett begins another address in the House of Representatives on the dangers of America's dependence on oil.

The Western Maryland Republican has given nearly 50 such speeches at the Capitol in the past three years, most of them variations on a theme: that a coming decline in petroleum production, coupled with growing demand for energy, will have a calamitous impact on the global economy.

"The world as a whole, and our country included, has appeared to behave as if these fossil fuels were inexhaustible," the former university professor lectures. "What we'll see shortly is that - as everyone will know, if you stop and think about it - that oil is finite."

This should be Bartlett's moment. With concerns growing about the impact of the use of fossil fuels on climate change, officials warning about the national security implications of relying on foreign oil, and the price of gasoline surpassing $4 a gallon, energy has become the nation's leading domestic political issue.

The 16-year House veteran has long prepared for the debate. A research scientist and inventor - he has a doctorate in human physiology and holds patents on breathing equipment used by astronauts, pilots and firefighters - he has spent years talking about, and getting ready for, a looming crisis.

... He refers frequently to reports commissioned by the federal government that predict dire consequences for failing to prepare for the moment when petroleum production begins to decline - a scenario known as peak oil.

The Government Accountability Office warned last year that a quick decline "would require sharp reductions in oil consumption, and the competition for increasingly scarce energy would drive up prices, possibly to unprecedented levels, causing severe economic damage. While these consequences would be felt globally, the United States, as the largest consumer of oil and one of the nations most heavily dependent on oil for transportation, may be especially vulnerable."

Bartlett believes that moment may now be arriving.