Each Tuesday night, the phone banks of Rep. Bruce A. Morrison (D-Conn.) in downtown New Haven are staffed by a score of hardy regulars: a few housewives, some college students, a librarian, a park ranger, a secretary. All are brought together by a single cause: nuclear arms control.

"The nuclear freeze people have built a reliable organization," said Paul Drolet, Morrison's campaign field director. "When they say they're going to produce, they produce."

It wasn't always so. Two years ago when Morrison, a legal aid attorney, was challenging incumbent Republican Lawrence DeNardis, the freeze movement was preoccupied with ballot referenda and educational seminars. Its impact in local congressional races was negligible.

This fall, in Morrison's tense rematch with DeNardis, volunteers organized by Freeze '84, a national political action group, have knocked on 10,000 doors in Connecticut's 3rd Congressional District. The group has its own New Haven office and a paid coordinator. It sends out mailings and will staff 30 precincts for Morrison on Election Day.

Across the country, the freeze movement has hit the political trenches -- if only a battalion compared with the field armies of their opposition.

This new activism was spurred by frustration with Congress, where the Senate has balked at passing a freeze resolution and the fate of the MX missile has hung on a two- or three-vote margin in the House.

"Up to now we've tried to change the politicians' minds," said Bill Curry, director of Freeze '84. "Now we're going to change the politicians."

Newly energized arms-control political action committees (PACs) are putting money where their muscle is. The Council for A Livable World expects to raise $1 million by Election Day -- almost double the amount it spent in 1982 -- and has already given $83,000 this year to Rep. Tom Harkin (D-Iowa) in his Senate race against incumbent Republican Roger W. Jepsen.

Freeze '84, which grew out of a conference of freeze groups in St. Louis last year, has raised $1 million but is spending it -- not on direct contributions to candidates -- but on organizing its own satellite PACs in 40 states. The state PACs, with paid staffs of as many as 30 people in California and six in New Hampshire, for example, have raised at least $2 million and have mobilized thousands of volunteers.

For the most part, however, their contributions -- mostly to Democratic campaigns -- are paltry compared with the resources of the national Republican committees and business PACs who finance their opponents.

The Committee for a Sane Nuclear Policy (SANE), one of the oldest arms-control groups, notes that in 1982 arms contractors made direct contributions of $2.5 million to congressional election campaigns. So far this year, SANE has contributed $80,000 to about 40 House and Senate candidates.

However, the numbers do not measure the impact of an activated constituency. When it looked like Dudley Dudley, a strong arms-control advocate, might lose last month's Democratic primary in New Hampshire's first congressional district, SANE's Boston office sent seven full-time volunteers to work during the last four days of her campaign. Dudley won the primary by about 1,000 votes but remains the underdog against real estate broker Robert Smith, a conservative Republican.

Despite the peace movement's greater involvement, arms-control and defense issues often take second place to economic issues, even in races targeted by arms control groups. Oregon's Rep. Les AuCoin (D), whose campaign is described by freeze activists as one of the most critical House elections in the nation, spends more time talking about unemployment in farming and the timber industry than he does about the MX.

AuCoin, who serves on the powerful defense appropriations subcommittee and has been a vocal leader in arms-control issues, has received $5,700 from SANE and $4,818 from Peacepac, an arm of the Council for A Livable World. His opponent, former Georgia Pacific executive Bill Moshofsky, also opposes the MX and the B1 bomber but has endorsed President Reagan's proposals for a new defensive arms system known as "Star Wars."

Moshofsky won 46 percent of the vote against AuCoin in 1982, and Republicans have focused on the race as potential switch seat this year.

Oregon freeze groups also are active in the campaign of State Sen. Ruth McFarland (D), who again is running against Rep. Denny Smith (R-Ore.). Two years ago, McFarland captured 49 percent of the vote despite a poorly organized campaign.

Volunteers from Political Action for Lasting Security, an Oregon peace group, are "a huge part of our field force," said McFarland campaign manager Barbara Cerepanya. "But we have a money problem. The peace groups can only give a small amount -- we got $2,000 from one Peacepac mailing -- but it's more than they've ever given before."

In Indiana, peace groups have contributed $6,200 to the campaign of Rep. Frank McCloskey (D), a dovish freshman on the Armed Services Committee. A former Bloomington mayor, McCloskey is neck and neck with State Rep. Rick McIntyre, a conservative Republican who has tied himself closely to Reagan.

In California, Rep. George E. Brown Jr. (D), a peace movement stalwart, is in a tight race with John Paul Stark, a San Bernardino businessman and former Campus Crusade for Christ official who got 46 percent of the vote in 1982.

Brown was the only House member to vote against the 1966 defense appropriations bill as a protest against the Vietnam war. This year, he led the opposition against Reagan's space weapons program. His district includes Norton Air Force base, research and development headquarters for the MX, which Stark supports and Brown does not.

Space weapons are also an issue in the heated race between Rep. Jerry M. Patterson (D-Calif.) and former GOP representative Bob Dornan, who moved into Patterson's district after losing a 1982 bid for the Senate. Dornan, a former fighter pilot and a nationally known conservative, is a champion of the B1 bomber and the "High Frontier" program.

In Utah, Frances Farley, a former state senator making her second congressional bid, has led Lt. Gov. David Monson in the polls. Farley, who headed the opposition to the MX during the heyday of the proposed "race-track" basing system in Utah and Nevada, has received more than $8,000 from peace PACs, but campaign manager John Becker said there has been little grass-roots activity by freeze groups.

In abandoning their white-gloved nonpartisan nature, peace groups recently have indulged in a bit of negative politicking, dubbing 12 congressmen the "Doomsday Dozen," or, as Peacepac literature explains, "hopeless nuclear hawks." Among the dozen: Rep. Denny Smith (R-Ore.), Rep. Frank R. Wolf (R-Va.), Rep. Herbert H. Bateman (R-Va.), Rep. Arlan Stangeland (R-Minn.), Rep. Don Ritter (R-Pa.) and Rep. Rod D. Chandler (R-Wash.)