The nuclear freeze movement took a step toward a more unilateral approach to U.S.-Soviet arms reductions today, voting in convention here to push Congress to cut off funds for weapons testing and "calling on" the Soviet Union to halt its tests.

The 600-plus delegates and observers defeated a move to make the drive "contingent on" the Soviet response. However, they sought to remain bilateral in leaving the door open to later support legislation that would allow U.S. tests to resume if the Soviet Union did not stop.

The complex program also put a new emphasis on the goals of European peace groups, elevating to a legislative priority new work in Congress against deployment of U.S. intermediate-range missiles in Europe later this year.

Organizers hammered at two themes: politics is long and time is fleeting.

"This is the critical year," said retired admiral Gene LaRocque, director of the Center for Defense Information in Washington. "If the Pentagon gets the money this year and starts the construction, it will be too late to turn it around."

In workshops, late-night strategy sessions and long meetings, leaders worked to patch up a division between freeze advocates who want a legislative focus and more street-oriented activists concerned with grassroots work. They urged expansion of the combined fund-raising, organizing and education work that they credited for endorsements of freeze initiatives by voters in nine states and the District of Columbia last year.

"Our job is continually to move back the frontiers of what is politically possible," Nuclear Weapons Freeze Campaign coordinator Randall Kehler told the opening session Friday night. He called a bilateral U.S.-Soviet freeze on weapons development "a new abolitionist move- ment . . . moving toward the abolition of war itself."

As expected, delegates agreed unanimously that everything in the legislative program depends upon winning clout this year and in 1984 with politicians at all levels.

"We have to talk their lingo," said Reuben McCornack, Washington representative for the freeze. "What we have to get through to them is, 'If you don't stop the arms race, your career in politics is finished.' " Demonstrations to that effect were approved for next fall.

The convention endorsed a special Project '84 Task Force to pick political "involvements" from among possible allies and candidates, decided on a field organizing project in the South and southwest where freeze sentiment is weakest, and planned wider public speaking, fund-raising and media efforts.

Kehler pleaded for more work in the money department, noting that last year's $544,000 budget left the national organization "stretched to the limit" and $14,000 in debt. The 1983 budget, he said, is just $650,000, "a pitiful little step."

What dissent there was focused on the degree to which freeze positions should depend on reciprocal Soviet acts. While the convention unanimously reaffirmed its goal of rousing Americans to press Washington to propose a U.S.-Soviet freeze on all weapons testing, development and deployment, "this administration is unlikely to do that," Kehler said.

"He would not only win reelection, he would go down as the greatest president of the 20th century. President Reagan is not smart enough to know that," said Randall Forsberg, a founder of the movement who now chairs its advisory board.

Kehler said that the resolution means that in the interim before the 1984 election, the freeze movement will press Congress to take the initiative by cutting off test funds, thus putting the ball in the Soviet court to do likewise.

The St. Louis University campus here took on some of the hoopla of a national political convention, with delegates from 47 states and 225 congressional districts, with songs and state pennants, balloons and emotional speeches. But the overwhelmingly white, middle-class crowd was almost paralyzingly knowledgeable about the arcane details of weapons systems, past and present arms proposals and the nuances of position-paper phrasing.

But the nondelegates were less certain of the fine points, crowding into workshops on how to deal with freeze critics, the nature of the Soviet threat, the legislative process and how arms levels can be verified.

The group was acutely aware of critics' charges that it does not speak to labor, blacks, the unemployed, or anyone without a college education.

Thus the convention elevated resolutions backing the Jobs for Peace Campaign and the Martin Luther King Memorial March in August to endorsements.