Los Angeles — Once again, California appears headed for the cutting edge of a national issue - in this case, the debate over the nuclear arms race.
That is the opinion of many observers tracking a signature drive aimed at placing a ''nuclear freeze'' initiative on the state's November ballot. If the drive is successful, and it appears that it will be, it will be the first time ever in the United States that such a measure has appeared on a statewide ballot.
The initiative, which urges President Reagan to propose to the Soviet Union that both nations agree to ''freeze'' all further testing, deployment, and production of nuclear weapons, is not legally binding.
However, against the backdrop of a growing national concern over nuclear proliferation, the initiative is expected to serve as a massive referendum on citizen misgivings about the nuclear arms race. Observers say its passage would be a highly symbolic vote which, coming from the largest state in the union, would be impossible to ignore, both at home and abroad. And, they speculate, it could even trigger similar initiatives elsewhere, just as Californians led the nation in a taxpayer revolt less than four years ago.
''It's a bellwether thing,'' says California pollster Mervin Field. ''Even if it doesn't pass, that doesn't make much difference. The positive effects will come from the debate, which will involve the same kind of soul-searching - although it may not be as heated - as the Vietnam war did.
''If it does pass,'' he continues, ''it will be a demonstration to the country's political leadership and to the world that we really want peace and are not committed to nuclear weapons.''
Since early December, when the campaign was kicked off, supporters say they have collected approximately 150,000 signatures - almost half of the 346,119 needed by April 22 to qualify the measure for the November ballot. The campaign has drawn a broad cross section of supporters, including Nobel scientists, church leaders, the state Democratic Party, the medical community, and a stellar collection of entertainers, including Mr. Reagan's daughter, Patti Davis.
''I see the initiative as the beginning of a broad citizen effort to bring moral, medical, scientific, and economic pressure to bear on the political process in this country,'' says Harold Willens, the LA businessman who is coordinating the campaign. ''I see it as a contemporary Paul Revere, which will sound the alarm and really begin to awaken the slumbering body politic.''
Organizers are careful, however, to distance the initiative as much as possible from partisan politics. They also hope to sidestep controversial issues such as nuclear power by confining the debate strictly to the nuclear arms race.
Observers like pollster Field note that the success of the initiative likely will ride on whether voters perceive it as a unilateral move that will cut US effectiveness in deterring Soviet aggression, or as a bilateral step to assure global peace.
Although there is as yet no organized opposition to the measure, proponents say they hope to dilute the impact of any arguments against the initiative by portraying it as an issue that cannot have two sides - that the question is one of life or human destruction. And, they note, the initiative has nothing to do with weakening the conventional defense capacities the public has favored strengthening.
''The growing danger of nuclear war is our No. 1 problem,'' Mr. Willens is fond of saying. ''Our No. 2 problem is that there are not enough people paying attention to our No. 1 problem.''