Clouds descended farther around the future of the Clean Air Act rewrite yesterday as the Senate Environment Committee wound up the first stage of its markup amid gloomy forecasts from three key Republicans.

Sen. Steven D. Symms (R-Idaho), who has emerged as chief defender of the Reagan administration position, warned the committee against any effort to deal with acid rain in its rewriting effort. "We'd be kissing goodbye for this year to any opportunity to make substantial improvements" in the 1970 law, he said.

But Sen. George Mitchell (D-Maine) and others have promised to propose mandatory reductions in sulfur dioxide emissions from electric utilities as an approach to reducing acid rain.

Symms said later he had not decided whether his opposition would extend to a filibuster. Earlier, at a National Association of Manufacturers briefing on air issues, Rep. Edward R. Madigan (R-Ill.) said it would take "something of a miracle" to wring legislation out of the House.

Madigan is ranking minority member of the Energy and Commerce subcommittee on health and environment, which is wrestling with the question now.

Major clashes were reported last week in private negotiating sessions among key House members, including Madigan, particularly over whether to ease restrictions on automobile emissions.

Sen. Robert T. Stafford (R-Vt.), chairman of the Environment and Public Works Committee, told the NAM briefing that the Senate leadership won't even bring to the floor a bill that will take more than a day and a half of debate. But committee members made clear that they are sharply split.

Sen. Gary Hart (D-Colo.) complained that the Reagan administration's reluctance to provide a detailed proposal meant the committee "is trying to legislate from a hodgepodge of official and unofficial documents." Symms said he was considering turning those documents into a coherent bill that he would offer on behalf of the administration.