A mysterious group called Republicans for Clean Air is broadcasting more than $ 2 million worth of television commercials in presidential primary states attacking Sen. John McCain and defending Texas Gov. George W. Bush's environmental record.

McCain campaign manager Rick Davis said yesterday he believes the ads--which are running in New York, California, Ohio and possibly other states--are the work of someone closely involved in Bush's campaign. But Davis offered no proof, and the Bush campaign denied involvement.

One person who was involved in the ad campaign said last evening the Bush operation had no connection to the commercials, but he identified two people who played some role in putting the ads on the air: Sam Wyly, a wealthy Dallas investor in alternative energy sources who is a major financial backer of the governor; and Jeb Hensarling, a Wyly consultant who used to work for Republican groups.

GOP consultants said the ads cost more than $ 2 million, including $ 1 million in New York state.

"We had nothing to do with these ads," said Bush campaign spokesman Ari Fleischer. "Senator McCain is once again mounting a divisive campaign vilifying . . . anyone with whom he has a principled policy difference."

"It's the oldest trick in the book to create a sham group to praise you on an issue where you are vulnerable," Davis said. "Bush is obviously trying to avoid being seen as an environmental hypocrite by getting someone else to falsely burnish his image."

The controversy over Republicans for Clean Air is a sign of the times: Anonymous groups with bulging bank accounts are increasingly using the airwaves to launch harsh denunciations of political foes without revealing who they are or where their money comes from. These groups say they do not have to reveal their donors or spending because they do not explicitly urge voters to support or defeat any candidate.

While environmental groups say that neither McCain nor Bush has a particularly good record on the environment, they are far more critical of Bush. Yesterday the Sierra Club, which itself has aired television commercials in California attacking his clean air performance, said the new pro-Bush ad is "littered with half truths." Bush stoutly defends his commitment to the environment.

Precious little could be learned initially about Republicans for Clean Air, which has not been an active organization before this week.

The ad company that purchased the commercials, complying with federal election law, told the television stations the identity of one of the organization's staff members, Lydia Meuret of Herndon.

But Meuret said she knows next to nothing about Republicans for Clean Air, except the "consultant" who hired her and told her not to reveal his name. She added that a news release would soon be distributed ending the mystery of who aired the ads. Yet there was no announcement.

Meuret serves as treasurer of the American Dream Political Action Committee, a GOP group that encourages Latinos to run for office. That group and Republicans for Clean Air share a post office box in Herndon.

American Dream PAC is heavily promoted by the GOP congressional leadership and financed by Republican-leaning business owners, particularly in Texas. A leading figure in the PAC is Rep. Henry Bonilla (R-Tex.), who endorsed Bush for president. Bonilla said through a spokesman yesterday that he knows nothing about the clean air group.

Hensarling was Meuret's predecessor at American Dream. Hensarling worked for years at the National Republican Senatorial Committee and the unsuccessful presidential campaign of Sen. Phil Gramm (R-Tex.) in 1996. Until two years ago, he was in the consulting business with James B. Francis Jr., a close Bush friend and his appointee to head the state's Public Safety Commission.

Hensarling, who declined comment about the matter, now consults for energy firms controlled by Wyly, among other clients. Wyly could not be reached. But days ago he and his brother Charles made $ 500 million selling a software firm they founded in 1981.

The ads attack McCain's environmental record, focusing on a vote against alternative energy sources, and tout Bush's performance, specifically Texas's effort to reduce emissions from aging power plants.

"Last year, John McCain voted against solar and renewable energy," begins the version of ad showing in New York City and five cities upstate. "That means more use of coal-burning plants that pollute our air. New York Republicans care about clean air. So does Governor Bush. He led one of the first states in America to clamp down on old coal-burning electric power plants. . . . Governor Bush: Leading so each day dawns brighter."