Andrew A. Samwick, chief economist on the Council of Economic Advisers from July 2003 to June 2004, and a professor of economics at Dartmouth, is a member in good standing. So is Martin S. Feldstein, the intellectual godfather of a generation of Republican economists. In June, Mr. Feldstein laid out his own Pigovian plan on the home page of Republican economic orthodoxy — the Wall Street Journal editorial page. The government, Mr. Feldstein said, should essentially ration gas by distributing tradable gas rights that entitle people to use gasoline. Those who don’t want to use them could sell them, and those who want to drive more would buy them. “The 50-cent price of the T.G.R. would have the same incentive effect as a 50-cent gasoline tax,” he wrote.

What gives? Clearly, there is an emerging consensus among economists — right and left — that the nation would be better off, geopolitically and economically, if Americans used less gasoline. “Given the role that imported oil plays today, you can’t continue to be a responsible economist and not talk about ways to reduce that dependence,” Mr. Samwick said. “If you are concerned about the external consequences of imported oil, then you should raise the cost of it.” And free-market economists view a higher gas tax as a more elegant solution than, for example, raising auto efficiency standards.

Others chalk up the rising chorus for a higher gas tax to a growing unity among economists across the political spectrum on the deleterious effects of global warming. “The U.S. has reasonable arguments for not signing the Kyoto treaty, but we need to propose some other measure that will help reduce emissions,” said Kenneth Rogoff, former chief economist at the International Monetary Fund and professor of economics at Harvard. A sharply higher tax on gas would help reduce consumption, and hence emissions.

But as much as Republican-leaning economists like Messrs. Greenspan, Mankiw and Samwick may think that it’s a good idea, the Republican politicians who control the levers of power in Washington think that it’s an awfully bad one, even though gas taxes in the United States are far lower than those in other industrialized countries. According to the International Energy Agency, American gas taxes in August were a mere 40 cents a gallon on average, compared with $4.24 a gallon in Britain and $3.99 in Germany.

The last increase in the federal gas tax was enacted as part of the so-called deficit reduction act of 1993, a package of spending cuts and tax hikes that didn’t receive a single Republican vote in Congress. And because President Bush and his top political advisers are known to be adamantly opposed to any increase in the gas tax, economic advisers haven’t pushed it much. “We didn’t have policy discussions about raising the gas tax,” Mr. Samwick recalls of his time in the White House.