It is good to see politicians, on that rare occasion, refuse to let partisanship get in the way of what is best.

Sens. Susan M. Collins and Olympia J. Snowe have done exactly that by breaking ranks with their fellow Republicans and supporting an effort to overturn new federal rules controlling mercury pollution.

Over the opposition of GOP leaders, Collins and Snowe put their names to a petition last week that gave it enough signatures to force a full Senate vote on the rules, which will help determine how much airborne mercury is allowed to drift into Maine in the years ahead.

To force a vote on the mercury resolution, 30 senators had to sign a petition to send the resolution directly to the Senate floor. Collins was the 30th senator, and the first Republican, to sign the petition, followed by Snowe.

We applaud the senators for putting Maine and its people-- especially children-- ahead of party politics. Highly polluting coal- and oil-burning power plants, after all, are a major cause of one of the largest environmental concerns-- and potential crises-- facing the state.

Like many environmentalists, including many Democrats, Collins and Snowe believe that the U.S. Environmental Protection Agency was too lenient in setting standards for mercury, a poisonous metal that is the primary cause of contamination in many of Maine's freshwater lakes and ponds and of the fish that live in them.

An estimated 80 percent of mercury pollution floats into the state, mostly from plants in the Midwest. The Bush administration's rules would allow three times as much pollution to reach Maine, according to the Natural Resources Council of Maine.

While many Republicans say they support the EPA's mercury standards, Collins and Snowe have not held back their criticisms.

"I'm very disappointed in the EPA rule," Collins said. "It's disturbing to me that EPA is proposing such a weak rule."

Added Snowe, "The EPA has refused to make any accommodation to those of us who have deeply held concerns regarding this rule. The stakes are too high for Congress not to have a say."

The petition requires a Senate vote within 60 legislative days, which means it could happen before August recess.

Even if the resolution passes in the Senate, the effort could be largely symbolic because it is likely to be opposed in the House of Representatives and by the president.

While that is regrettable, Collins and Snowe deserve credit for forcing the vote.

It should at least bring greater attention to mercury pollution, especially in Maine, and point out problems within the EPA.