The Reagan administration yesterday endorsed a proposed rewriting of the Clean Air Act for the first time, indicating that the stalled debate may truly get going when Congress returns next week.

If it does, two House Democrats, including Energy Committee Chairman John Dingell (D-Mich.), will be leading the charge for the Republican administration.

Environmental Protection Agency Administrator Anne M. Gorsuch told an industry-labor group yesterday that she was "very pleased" with a bill introduced just before Christmas by Rep. Thomas A. Luken (D-Ohio). She added that Vice President George Bush will help her push for it.

Luken claims strong support from business and labor, saying the only groups not on board are the environmentalists. And he's not giving up on them.

But environmentalists say Luken doesn't have the support he thinks he does. The Natural Resources Defense Council and the National Audubon Society called the bill "a dirty-air Christmas present to the nation" that "cuts to the heart of the basic federal clean-air program."

Dingell, whose automaker constituency is pushing to know what rules it will have for its new models, has been chafing at the prolonged hearings Rep. Henry A. Waxman (D-Calif.) has held in his health and environment subcommittee. Rep. James T. Broyhill (D-N.C.), a cosponsor of Luken's bill and ranking minority member of the Energy Committee, has asked Dingell to consider bypassing the subcommittee to work on the Luken bill, but that would cause an uproar among the Democrats.

Luken's bipartisan measure does not try to remove distinctions in the law between high-sulfur and low-sulfur coal burning at utilities, which is a major goal of the public utility industry. Neither does it ease controls on toxic air pollutants, as the chemical industry would like. But environmentalists had sought tougher restrictions in both areas, and those industries are expected to join in backing the Luken measure.

The Luken proposal would:

* Allow the EPA to extend the 1982 and 1987 state deadlines for cleaning their air to 1993 if the states guarantee compliance by then.

* Make it easier for businesses to locate in areas with dirty air by replacing the requirement that they achieve the "lowest achievable emissions rate" with a call for the "best available control technology," which is less restrictive but most used in practice.

* Allow auto inspection and maintenance programs to end in cities of less than 500,000 people where air pollution is no more than 50 percent above health limits.

* Eliminate penalties for states that fail to submit plans for implementing the Clean Air Act, while expediting the federal review and approval process for changing those plans.

* Eliminate the complex system of figuring each plant's contribution to a regional air pollution level.