After he had finished his $14 dinner of salmon and baked potato, Vicente Garza was worried about the Russians, worried whether you could trust a nation that said to America, "We will bury you."

And he made his worries known to the vice president of the United States. "How do you resolve, Mr. Vice President, the dilemma of the public over a Soviet leadership that says they are out to dominate the world?"

In short, Garza arrived opposed to the strategic arms limitation treaty (SALT II) that the United States has negotiated with the Soviet Union. But by the time Mondale was through answering Garza the other night, Garza reconsidered his opposition and said, "No, not anymore."

That was exactly why Mondale had come to Oregon, to change the minds of people like Garza.

For five days last week, Mondale stumped seven states on a key SALT-selling spree. It was part of the most important, most expensive administration campaign yet to win public support for public policy.

No surprisingly, Mondale's trip was put together with a hard political reality. The seven states - (California, Oregon, Kansas, Nebraska, South Dakota, Tennessee and Pennsylvania) account for 14 U.S. senators, 10 of whom are publicly uncommitted on SALT. Nor has the administration written off three other senators from those states who have expressed reservations about SALT II.

Whatever Mondale's success in winning support for SALT II, and random interviews revealed some, what the vice president found was a public genuinely concerned about the nuclear arms race and seriously interested in weighing the new treaty itself.

Judging from the questions, there also were fears of Soviet superiority in weaponry or cheating on arms agreements.

The houses were packed and, despite political upheaval in Washington, the audience's questions were uniformally about SALT. Crowds that were so attentive and motionless that they appeared to be glazed over with boredom burst into applause at varying points.

"They're listening, you can tell," Mondale reflected while relaxing on his Air Force jet between Portland, Ore., and Topeka, Kan. "Now, that's complicated stuff, and they're hanging on. People are trying to be good citizens."

What Mondale gave them was the same message the administration is pressing on the Senate to win approval of SALT - that the pact is in the best interests of the United States and that the country will be better off with it than without it.

"I came in here very much against SALT," said Dr. I.M. Vigran, 62, after Mondale's talk to the Los Angeles World Affairs Council. "But I think he has changed my mind. I've listened to people who say we can't monitor the agreement, but he has convinced me that is secondary to the magnitude of the weaponry.

"Much more would be lost if we didn't ratify the treaty than if we did . . . I think I will send telegrams to my senators."

While Mondale refuted any notion that his trip was designed to bring pressure on the states' senators, aides noted that it was intended to build public support to help the senators make up their minds or to minimize the political damages to those already in favor of SALT II.

Mondale's trip provided a glimpse of the inside machinery of the Carter administration's campaign to win Senate approval of SALT II, a complicated and temporary measure to limit the nuclear arsenals of the two superpowers.

Mondale staff members Jim Johnson and Beckie McGowan put the trip together first by selecting from their files requests for a vice presidential speech.

In a few instances, such as in the case of Nebraska, they sought the best group for Mondale to address. All the time, they kept in mind how each state's senators viewed SALT.

In Nebraska, for example, Democratic Sens. J. James Exon and Edward Zorinsky are uncommitted.

Other concerns wre to visit scattered parts of the country and speak to crowds with mixed opinions so that Mondale could address, in Johnson's words, "The arguments and reservations and other material" that will mark the SALT debate.

"We wanted a broad range, skeptics as well as the supporters8" McGowan said. "We wanted informed people in those states, people who make their views known, people with secondary impact."

The result, in part, was unusually long sessions with editors, reporters and editorial writers who will deal with SALT.

And what happened was, seven speeches to groups such as the World Affairs Council and the League of Women Voters, seven press conferences, four editorial conferences, 12 "exclusive" television interviews, a 30-minute public affairs show on Portland television and a public television excerpt of a meeting with reporters.

The effort was considered so crucial that the White House's top SALT expert, Roger Molander of the National Security Council, was sent along, despite some desires to keep him in Washington for Senate hearings on SALT.

On the initial leg of Mondale's trip, from Washington to Los Angeles, the vice president and Molander reviewed a 36-page notebook inscribed "SALT II Q & As" - 15 questions frequently raised by opponents of the treaty and extended answers to them.

Molander, who said he found Mondale well-informed on SALT, was the vice president's technical expert on the treaty. The 38-year-old Molander had spent five years negotiating it, and he provided the numbers and technical details of Soviet and U.S. weaponry.

In private, Molander said what he thinks SALT will help do and what he fervently wants it to do: "We want to slow the momentum [toward new Soviet weapons], take the guts out of their design bureaus. We want those people to build electric toothbrushes instead."(TABLE)(KEY OFF)(KEYWORD)dministration official out selling SALT. Defense Secretary Harold Brown also have been on the hustings. Washington attorney Llloyd N. Cutler has been chosen to orchestrate the administration's efforts on Capitol Hill. The White House has invited people from around the country to Washington for SALT briefings, and the top Soviet expert on U.S. affairs has been campaigning in this country for approval of the treaty. And a campaign it is, right down to the man in Mondale's entourage who sported a blue-and-white "Pass SALT II" button.(COLUMN)The trip, also in true campaign style, consisted of what is known in politics as The Basic Speech.(COLUMN)Mondale, who 35 years ago was a pea lice inspector for the Jolly Green Giant in Minnesota, hammered away at the thought and prospect of nuclear holocaust. He repated the administration's belief that the treaty would benefit U.S. security, not weaken it, and that those who want greater arms reductions must accept SALT II as a necessary step toward that goal.(COLUMN)"This is not based on trust," he told his audiences. "This is based on our experience and our technical ability" (to assure Soviet complaince).(COLUMN)"Without SALT, everything will be worse, more costly. I am no admirer of the Soviet system. We're doing this for us, not for them," Mondale said. He said more than once the final decision on SALT will be made not in Washington "but in the cities, the towns, the homes and the farms of America."(COLUMN)And that, he hopes, will result in Senate approval of a treaty he sees as designed to reduce the possibility of nuclear disintegration while still leaving the United States strong. (END TABLE) CAPTION: (TABLE) Picture, no caption, The Washington Post (END TABLE)