Tired of shooting blanks at the United States over acid rain, the Canadian government admits its campaign to reduce emissions that cause the environmental hazard has fizzled out.

"We are making progress with American public opinion, just as we are increasing the number of allies in the legislative branches at state and national levels," said Canadian Environment Minister Tom McMillan."But, admittedly, we are not making the kind of progress we had hoped to make and still hope to make with the American president."

In a recent speech to New York businessmen, Prime Minister Brian Mulroney warned that U.S. inaction on acid rain could harm relations between the countries.

Although public opinion polls suggest Americans are more aware of the consequences of letting acid rain continue unabated, there is no indication the Reagan administration is prepared to legislate reductions in sulfur dioxide emissions from coal burning plants.

Despite harsh words, McMillan said there is little Canada can do beyond lobbying key U.S. senators and raising the issue at the annual summit between Mulroney and President Reagan, scheduled for April 26-28 in Washington.

When the two leaders met last year in Ottawa, Reagan told Parliament he would consider Canada's proposal for an accord along the lines of an existing treaty dealing with shared water resources.

But U.S. officials rejected the proposed treaty, drafted by Canada and presented last May, to cut U.S. emissions in half by 1994, a schedule identical to one already adopted by all 10 Canadian provinces.

Alex Manson, director of Canada's acid rain program and one of the senior negotiators of the proposed treaty, said the administration is opposed to any agreement that sets specific emission control targets and schedules.

"Without specific targets and schedules, you haven't got anything that deals with the problem, only something that debates whether you have a problem," he said. "The problem of acid rain has been demonstrated in spades."

Instead, he said, U.S. officials want an agreement that essentially would further define the problem and establish mechanisms for joint research and information sharing.

That may have been an appropriate solution eight years ago, Manson said, but scientists in both countries now have compiled vast amounts of information on acid rain.

McMillan said his government ruled out legal action against the United States, even though damage from U.S. emissions amounts to hundreds of millions of dollars.