Rep. Stan Parris, struggling to revive his sagging bid for the Republican nomination for governor of Virginia, faces a critical test in his Fairfax County base tonight, where opponent Wyatt B. Durrette hopes to knock him out of the race.

"If I lose Fairfax County, it's lights out in Dodge City," Parris said yesterday.

His comments came on the eve of eight GOP mass meetings in the county that will select the largest block of delegates any jurisdiction will send to the party's state nominating convention in Norfolk this spring.

Fairfax alone can provide one-fourth of the delegate votes needed to win the nomination. Both Parris and Durrette, a Richmond attorney and former state legislator from Fairfax, have agreed that tonight's meetings could be pivotal.

"We're gonna do whatever we have to do to win it," Parris said in an interview. He conceded his campaign may attempt to use a controversial procedural maneuver that would bind some Durrette delegates to vote for Parris at the convention in order to win positions in the Fairfax delegation.

"If his maneuver works, he Parris will still be in the race," Durrette warned his supporters in a recent fund-raising letter. (The maneuver, called instructing, allows a candidate with a majority of the delegates present at the meeting to bind the entire delegate block to the majority's candidate at the state convention.)

The Durrette camp said it will use its own political tactics to try to head off a Parris sweep in districts where the congressman is weakest. And even if Parris succeeds, some Durrette campaign aides were attempting to play down the significance.

"You expect a man to win in his own backyard," said Durrette campaign spokesman Don Harrison. "But if Stan wins the whole shooting match, it's not enough; it's too little, too late."

With slightly more than one-half of the 3,900 Republican delegates statewide selected, the Durrette campaign says it has captured 85 percent of the delegate votes it needs to win the nomination. The Parris campaign agrees that the Durrette campaign is significantly ahead, but says Durrette has won only 67 percent of the delegates required for nomination.

Although 535 votes are at stake in Fairfax tonight, the votes could be divided in many combinations because the delegates will be selected at eight separate district meetings.

The maneuvering by the two camps is compounded because four of the districts are in Parris' 8th Congressional District and four are in the 10th Congressional District where Parris' colleague, Rep. Frank R. Wolf, is supporting Durrette.

It is in the 10th District -- northern Fairfax -- where Durrette forces will try to head off a Parris sweep. The Parris campaign said yesterday it expects Durrette forces to control at least two of those districts, an area Durrette once represented in the House of Delegates.

Another complication is the impact of the lieutenant governor's race. Fairfax is home to candidates J. Marshall Coleman, the former state attorney general who ran unsuccessfully for governor against Democratic Gov. Charles S. Robb, Richard A. Viguerie, a founder of the New Right direct-mail movement who is making his debut in state politics, and lobbyist Maurice Dawkins of Springfield.

Also fighting for the nomination for lieutenant governor are state Sen. John Chichester of Fredericksburg and state Del. A.R. (Pete) Giesen of Augusta County.

The Republican mass meetings will be held in Fairfax's eight magisterial districts beginning at 8 p.m. Registration will open at 6 p.m.

The locations:

Annandale: Lake Braddock Secondary School cafeteria, 9200 Burke Lake Rd., Burke.

Centreville: James Madison High School, 2500 James Madison Dr., Vienna.

Dranesville: Cooper Intermediate School, 977 Balls Hill Rd., McLean.

Lee: Mark Twain Intermediate School, 4700 Franconia Rd., south of Alexandria.

Mason: Holmes Intermediate School 6525 Montrose St., near Alexandria.

Mount Vernon: Mount Vernon High School, 8515 Old Mount Vernon Rd., south of Alexandria.

Providence: Marshall High School, 7731 Leesburg Pike, near Falls Church.

Springfield: Irving Intermediate School, 8100 Old Keene Mill Rd., near Springfield.