WASHINGTON – The Bush administration clashed with senators Monday over new rules limiting mercury emissions from power plants with the White House threatening a presidential veto of Senate legislation that would overturn those rules.

The Senate agreed to vote Tuesday on a resolution that would negate the Environmental Protection Agency rules from last March. Those rules are opposed by environmental and health groups demanding swifter and tougher measures to reduce emissions of the toxic metal.

The Senate vote is expected to be close, but the resolution is unlikely to see action in the GOP-dominated House and would have no chance of surviving a presidential veto.

The administration claims its market-based approach will eventually cut mercury emissions from coal-fired power plants by 70 percent without driving up energy costs and says repealing the rules “would unnecessarily delay the first-ever reduction” of such emissions.

But opponents say the rules favor the utility industry at the expense of public health. “Every freshwater river, lake and stream in my state is subject to a mercury advisory warning pregnant women and young children to limit consumption of fish caught in these waters,” said Sen. Susan Collins, R-Maine, sponsor of the resolution with Sen. Patrick Leahy, D-Vt.

If the rules stand, she said, “power plants will be free to continue spewing unlimited amounts of toxic mercury into our air until the year 2018.”

Sen. Olympia Snowe of Maine also supported the resolution.

Leahy and Collins turned to a little-used 1996 law that allows Congress to challenge agency rules with a guaranteed floor vote. The law has been successfully invoked only once, when Congress in 2001 repealed Clinton administration workplace ergonomics regulations.

By repealing the EPA rules, the Senate would compel the agency to rewrite the rules. The revisions would be in line with Clean Air Act standards requiring the use of the best available technology to reduce mercury emissions.

Leahy said the Clean Air Act would start reductions in 2008. They would achieve up to 90 percent reductions far sooner than the EPA rules that, according to Leahy, don’t begin to cut emissions until 2018 and will not reach the goal of 70 percent reductions until 2030.

Environmental and health groups and other opponents of the new rules say the regulations are inadequate in dealing with a toxin that every year puts hundreds of thousands of newborns and children at risk of neurological damage. Mercury pollutants work their way up the food chain after being absorbed by fish.

But supporters of the EPA rules said repealing the administration approach could have a devastating impact on the economy, forcing power plants to abandon coal for natural gas and driving up natural gas prices.