Four Northern Virginia politicians, frustrated because they don't know when, or if, the region can begin selecting candidates for the House of Delegates, turned yesterday to a federal court for help.

The four filed suit in U.S. District Court in Alexandria pleading for speedy consideration of Virginia's House reapportionment plan, which has been snarled by legal challenges almost since it was approved this spring by the General Assembly.

All 100 of the House seats are up for grabs this year, and numerous politicians are complaining they can't begin planning their election campaigns until the courts and the Justice Department approve the reapportionment plan. Although House primaries tentatively have been scheduled for Sept. 8, many prospective candidates say they are afraid that delays by the courts and Justice Department will postpone approval of the plan until long after the Aug. 7 filing deadline.

"I'm kind of reluctant to ask people to contribute to my campaign if there's some question as to whether I'm going to be running and what I'll be running for," said Norborne Beville Jr., one of the plaintiffs in yesterday's lawsuit.

Beville, a Manassas lawyer, said he is considering running for the House from Prince William County, but said the redistricting issue is so confusing that he's not sure whether to buy campaign posters or sit it out until the next election. Depending what the courts and the Justice Department do, he could find himself in a newly created three-member district that includes Prince William, Manassas and Manassas Park and has one open seat, an old three-member district that includes Prince William and Loudoun counties and has no vacant seat, or an entirely new court-ordered district.

The three incumbent legislators from his district -- Dels. David E. Brickley, Earl E. Bell and Floyd C. bagley -- have been popular and Beville said he didn't want to have to oppose them because they are "my friends."

"We're asking that all matters be decided as quickly as possible so that redistricting can go into effect for the 1981 candidate selection process," said Beville. He was joined in the suit by G. Richard Pfitzner, a member of the Prince William Board of Supervisors; Charles J. Colgan Jr. of Manassas, son of Democratic state Sen. Charles Colgan, and Odis M. Price of Dale City.

Yesterday's lawsuit by the four Northern Virginians bring to six the number of court challenges that have been filed against the Virginia House plan. It is the first to seek a quick, court-ordered settlement of the issue. The other charge that the plan violates constitutional guarantees of equal voter representation. The NAACP has also filed a complaint with the Justice Department, which must review the proposal under the Voting Right Act, charging that the plan dilutes black voting strength.

Potential candidates say they are especially troubled by a Justice Department statement last week that it may need up to 60 more days to evaluate the NAACP complaint. They say that announcement, coupled with a decision by District Judge D. Dortch Warriner to postpone a hearing on the issues until Aug. 13, could mean that the case will not be resolved until after the Nov. 3 elections.

"It's just a mess," says Conrad J. Marshall, a Democratic candidate in what is supposed to be a three member House district in northeast Fairfax County. "You end up planning two campaigns at once, in effect -- one in your old district and one in your new one."

Because rapidly growing Fairfax County picked up two additional delegates in this year's reapportionment, politicians there are adamant in opposing any suggestion that candidates run in their old legislative districts. o

Last week, a bipartisan group of county politicians led by Board Chairman John F. Herrity pledge the county's assistance in fighting any reapportionment plan that could drop Fairfax's House representation from the 12 granted under the new plan. "I don't think it's in the best interest of Fairfax County to sit idly by while our right to the provision of one man, one vote disappears," said Herrity. "We will intervene to protect Fairfax County's interest."

The state's last reapportionment struggle, which began in 1971, was not settled until 1973.