Rep. Paul S. Trible Jr. has been working for more than a year toward capturing the Republican nomination for the U.S. Senate in Virginia, but a survey taken last week in behalf of Rep. Stanford E. Parris of Woodbridge found three out of four party activists uncommitted.

Parris supporters said they contacted 100 party leaders, representing each of the state's 10 congressional districts, and found 13 committed to Trible and 11 leaning toward him. Nine others said they would support Parris if he ran, and six more said they leaned toward Parris, a spokesman for Parris said. The other 61 people surveyed had no favorite, the Parris aide said.

Parris is expected to decide in the next 10 days whether to pursue the nomination, which became wide open after three-term Sen. Harry F. Byrd Jr., an independent, announced last month that he will retire. In addition to the survey of party leaders, Parris boosters have talked to several campaign specialists, including a media consultant.

Trible's early start has produced commitments from at least three of the 10 district chairmen, but Parris supporters said that because of Trible's unwillingness to announce his candidacy until he learned what Byrd would do, much of his support is soft.

In weighing a Senate race, both Trible and Parris must decide what to do about their respective House seats, which also are up next year.

If Parris seeks reelection to the House, he is almost certain to face a serious challenge from Democrat Herbert E. Harris II, who has kept open his campaign office since his defeat by Parris in 1980.

Harris unseated Parris in 1974, in the aftermath of Watergate, and held the seat for six years. Parris has said he doesn't want to "turn over the seat to Herb. I would have to be sure we could find a strong nominee," before opting for a Senate race.

Trible has piled up overwhelming margins in being elected three times in the 1st District, which runs north from Hampton along the Atlantic coast, and his reelection is believed to be secure. Trible may be able to hedge his bet, by delaying his decision about the House seat until after the Senate candidate is picked at the state convention in Richmond June 3 and 4.

Dudley Lewis, 1st District GOP chairman, said Friday that postponing the House nominating process until after the Senate nominee is selected "has been mentioned as an alternative." The date for picking the House nominee will be made next month by the 1st District Republican Committee, Lewis said.

Lewis said Trible "will come as close to 100 percent as you can ever get" in support for the Senate among Republicans in his district. Other district chairmen behind Trible are Barney Annas of Virginia Beach and Richard Martin of Roanoke.

John S. Reid, a Richmond school principal and 3rd District GOP chairman, said he wants to see how much money Trible can attract from the traditional Main Street financiers in Richmond and be satisfied that Trible can run well with various voting blocks.

Reid said Republicans should have learned from last month's Democratic sweep of state offices that the party cannot write off blocs of voters, such as blacks and labor, and win statewide. He is leaning to Trible, he said. "Paul has shown he can run well in a tough district," which has large labor, black and rural voting groups, he said.

Several party leaders said neither Trible nor Parris offer the wide appeal that would come from nominating Gov. John N. Dalton, who said he will retire when his term expires next month, or Wyatt B. Durrette, the Fairfax lawyer who barely lost in the attorney general race last month. But Dalton and Durrette repeated last week their unwillingness to run.

Durrette, who is still more than $70,000 in debt from his defeat, said he might accept the nomination if he could get it without a fight, but he doesn't see that as a likelihood. Durrette said he has not given his support to anyone yet.

Despite Trible's generally conservative voting record during five years in the House, some New Right leaders are encouraging Parris to challenge him. One of them is Paul Weyrich of the Committee for the Survival of a Free Congress. Weyrich said Trible irked some New Right leaders, who consider conservatism more important than party affiliation, by attending a fund-raiser for the Republican opponent of Rep. Larry McDonald (D-Ga.), one of the House's most conservative members.

Although Parris' voting record may not be as conservative as Trible's, he is expected to portray himself as more consistent and mature than the 34-year-old Newport News congressman, in an attempt to attract independents and conservative Democrats who hold the balance in Virginia elections.