Associated Press President Bush wields an axe during a snowfall as he helps volunteers work on the trail near the AuSable River in Wilmington, N.Y., yesterday. Bush marked Earth Day with a pitch for his air pollution-reduction strategy in New York state's Adirondack Mountains, which are threatened by acid rain

In their sharpest clash since the 2000 campaign, President Bush and Al Gore are giving dueling Earth Day speeches - Bush touting his plan to combat air pollution and his former rival contending the White House is sabotaging environmental protections.

Bush was spotlighting a market-based proposal he has promised will deliver "dramatic progress" in air quality. He was making his pitch yesterday at Lake Everest, in New York state's acid rain-plagued Adirondack Mountains.

The president has asked Congress to approve mandatory limits on total industry output of three kinds of pollutants and to let companies work out how to achieve them through a system of earning and trading credits. The pollutants are acid rain-causing sulfur dioxide, smog-causing nitrogen oxide and mercury, a toxic chemical that contaminates waterways and goes up the food chain through fish to people.

Under his "Clear Skies" plan, Bush maintains, each pollutant would be reduced by about 70 percent by 2018. Congress has yet to vote on his proposal.

Gore contends the plan would ultimately allow more emissions of each than under current law.

"Put simply, on the environment, this administration has consistently sold out America's future in return for short-term political gains," the 2000 Democratic presidential nominee said in a New York Times guest column Sunday. Aides said his speech at Vanderbilt University in Nashville, Tenn. - scheduled to begin 25 minutes after Bush's - would echo the article.

In response to Gore's criticism, White House spokesman Ari Fleischer said: "I think that has more to do with internal Democratic posturing than it does with any serious assessment of the president's environmental record. After all, (Gore) in an era of peace and prosperity made the same charges in the campaign and the voters elected President Bush."

Bush, walking through the snowy woods near Au Sable River, said when he was asked about Gore's criticism he "hadn't paid attention to him." Told that Gore criticized Bush's environmental record, the president said, "That's why I haven't paid attention to him."

Bush's hair was flaked with snow as he walked a wooded trail and stopped along the way to help fix it up. At one point he drove a large nail through a log with the back of an ax, the sharp end coming within a few inches of his forehead with every thrust. Bush's face turned deep red and he gave a deep sigh as he finished the project. Bush held the ax triumphantly in the air when he finished the project and then waved to reporters and said, "Get them moving, that way I won't have to nail so many of these things."

Bush then used a regular hammer and smaller nails to fasten boards to logs higher up the trail to make a bridge. Wearing khaki pants and a tan leather jacket, Bush was on his knees as he hammered the bridge, soaking his pants with the melting snow.

The walk in the woods was designed to give a pretty backdrop to Bush's environmental speech. Ninety degree temperatures in Wilmington, which is near the Lake Placed Olympic site, gave way earlier this week to freezing temperatures. A thin layer of snow, which blanketed the woods, began falling as Air Force One arrived in New York.

The Adirondack Council and some other environmental groups in upstate New York have embraced Bush's plan, which was modeled after the Environmental Protection Agency's program for reducing acid rain.

"It is based on a highly successful program and we're just expanding that to three of the top pollutants," EPA spokesman Joe Martyak said. "Clear Skies is the best solution right now to dealing with some of our biggest pollution and related public health issues."

But other environmental groups warn that the plan would be a step backward from goals set by Clean Air Act regulations already on the books.

Some critics say it would reduce scrutiny of power plant emissions and roll back Clinton administration enforcement programs.

Acid rain is caused when pollutants are carried east on winds from Midwest smokestacks and mix with water vapor in clouds over the Adirondacks.

The Adirondack Council estimates that 500 to 700 of the wilderness area's 2,800 lakes are already too acidic to support native fish and plants. In addition, much of the high-elevation spruce has been damaged and some unique strains of trout have disappeared. By 2040, as much as half of the Adirondacks' lakes and ponds could be killed by acid rain, the group says.

In an EPA-funded study, however, researchers at Rensselaer Polytechnic Institute in Troy, N.Y., reported in February that acidic levels decreased moderately in 18 of the 30 Adirondack lakes it monitored from 1994 to 2000. Other lakes showed no signs of improvement.

Democrats have been searching for an issue on which Bush is vulnerable during a wartime period when he enjoys high approval ratings. Polls say the public regards Democrats as more likely than Republicans - by 20 to 30 percentage points - to give domestic issues such as the environment a high priority.

Gore, who wrote the environmental book "Earth in the Balance," has latched onto the issue. He accused the administration of handing over authorship of its energy policy to energy companies who donated to Bush's 2000 campaign, and of favoring increased domestic oil production over conservation.