WASHINGTON — Supporters of climate-change legislation are using a surprising figure to promote their cause: Ronald Reagan.

Radio ads asking “What would Reagan do?” are airing during the conservative talk shows of Rush Limbaugh and Glenn Beck in New Hampshire and are planned in other states in the drive to get Congress to act on global warming legislation.

The ads, which include clips from Reagan speeches, are the work of Republicans for Environmental Protection. They come as a group of senators works to draft a bill that can attract bipartisan support.

Although it may seem unusual to find President Reagan – who frequently antagonized environmentalists – in a campaign to promote environmental regulation, the group said the ads are designed to show that concern about climate change is “consistent with true conservative values.”

“What is a conservative after all but one who conserves, one who is committed to protecting and holding close the things by which we live,” Reagan’s voice intones in one of the ads, from his 1984 speech to the National Geographic Society. Republicans for Environmental Protection’s Web site offers a transcript of the full speech, in which Reagan says, “And we want to protect and conserve the land on which we live – our countryside, our rivers and mountains, our plains and meadows and forests.”

Environmentalists thought the ads were an April Fools’ joke. “They must believe, as author Gore Vidal put it, that we live in the United States of Amnesia,” said Frank O’Donnell, president of Clean Air Watch.

Critics of climate-change legislation were taken aback, too.

“I can say with no hesitation that Ronald Reagan, were he alive today, would not believe that global warming was a crisis and would not support energy-rationing legislation,” said Myron Ebell, director of energy and global warming policy at the pro-market Competitive Enterprise Institute.