Washington — The nuclear freeze movement is poised to become a key issue in the 1984 election. Yesterday, a pro-freeze political action committee announced the first of what will be some 40 endorsements for the House and Senate. Pro-freeze organizers with ''Freeze Voter '84'' are now in 150 cities across 38 states canvassing voters and raising money. They have already helped Democratic Rep. Paul Simon in his bid to unseat Republican Sen. Charles Percy of Illinois.
This week, a bipartisan group of lawmakers introduced ''quick freeze'' legislation that would halt the testing and deployment of new ballistic missiles and antisatellite (ASAT) weapons as well as underground nuclear explosions by both the United States and the Soviet Union. The bill has 90 cosponsors, a number that continues to grow daily.
Also this week, presidential hopeful Walter Mondale called for a freeze on anti-satellite weapons testing. He also supports the broader freeze issue, as do his Democratic rivals Gary Hart and Jesse Jackson.
Between 70 and 80 percent of Americans polled favor a mutual and verifiable nuclear weapons freeze. A survey by the relatively hawkish Committee on the Present Danger last week confirmed this. The proposal has passed House muster by wide margins, but so far has been stymied in the GOP-dominated Senate.
But with the Geneva arms control talks currently stalled, frosty US-Soviet relations, and growing public and congressional concern about the Reagan administration's push for ASAT weapons and a new strategic defense initiative (the space-based ''Star Wars'' option), freeze backers see this election year as ripe for victory.
''First we tried to change the politicians' minds,'' says ''Freeze Voter '84 '' spokesman David Heckman. ''Now we're going to change the politicians.''
''Once a clear consensus emerges among our supporters, we will endorse a presidential candidate,'' he adds.
The movement has been gaining steady support beyond its hard-core grass-roots activists and the hundreds of city councils and town meetings that have endorsed the freeze. The 111,000-member League of Women Voters, in what it called ''its first foray into the arms control debate,'' late last year endorsed a bilateral, verifiable freeze on the testing, production, and deployment of nuclear weapons. The vast majority of labor unions also back the freeze.
The freeze resolution passed 278 to 149 in the House of Representatives last year. But supporters of the ''quick freeze'' legislative moratorium on nuclear weapons testing admit that this new initiative - essentially a ''put up or shut up'' challenge to Congress as well as the Soviet Union - could be more difficult to achieve.
''There's no question that it's going to be tougher for us,'' said Randall Kehler, national coordinator of the Nuclear Weapons Freeze Campaign. ''We understand this is a longer-term legislative effort.''
This measure, less than a comprehensive freeze, would halt those strategic nuclear activities judged to be easiest to verify by satellite, seismic monitoring, and other surveillance means: ballistic missile launchings, weapons fired at targets in space, and underground explosions. These include the US MX land-based and Trident II submarine-based missiles, and three new Soviet missiles now being tested.
Because of serious verification problems, this interim measure does not address cruise missiles or ballistic missile production. Instead, it presumes that these more difficult issues will be taken up in later negotiations.
''This legislation is not based on trusting the Soviets,'' stressed Rep. Edward J. Markey (D) of Massachusetts in introducing the bill Wednesday. ''Every component must be verified.''
If passed, the proposed ''Arms Race Moratorium Act'' would require the President to seek such a limited freeze with the Soviet Union. If Moscow agreed, no money could be spent for those specified testing and deployment activities. If the President certified to Congress that the Soviet Union had violated the terms of the agreement, however, the funding could be immediately resumed.
''This proposal will have important strategic security advantages for the United States,'' says Jeremy Stone, director of the Federation of American Scientists.
Pointing out that the Soviet Union at present has more new missile-production lines open than the US, he adds: ''It does more to halt Soviet deployment than it does to halt our deployment.''
The Reagan administration does not favor a nuclear freeze, officials say, at least until the US has such new weapons as the MX in place. But pointing to the large number of nuclear warheads already in both countries' arsenals, other Republicans disagree.
''Arms control simply cannot be prudently postponed,'' says Rep. Jim Leach (R) of Iowa, a former Foreign Service officer who represented the US at the Geneva Disarmament Conference and now favors the freeze.
And in recently announcing his candidacy for the US Senate from Massachusetts , Elliot Richardson (who took part in early strategic arms limitation talks with the Soviet Union) pledged to ''intensify efforts'' to freeze, then reduce nuclear weapons.