It was morning rush hour on the George Washington Parkway when Frank Medico, a certified public accountant, pulled off his latest ploy. Flanked by two attractive teen-age girls, Medico enthusiastically waved placards at passing motorists and encouraged them to honk in response.

Medico, a first-time Republican candidate for the Virginia House of Delegates, said it was a simple, low-cost method of getting his name across to voters in southeast Fairfax County's 52nd House district. And since name recognition is said by many candidates to be half the campaign, Medico's scheme may be just the approach to an election that has been plagued by uncertainties.

To many, just holding Tuesday's 11 Northern Virginia primaries is a major accomplishment in a year snarled by confusion over when -- and if -- the 100-member House would stand for election. Until a three-judge federal panel handed down a decision two weeks ago ordering fall elections, Virginia's legislative candidates were not certain whether the primaries would be held, or what the boundaries of their districts would be.

"I keep running into old friends who say, 'Really? Is it next Tuesday?' " said Democratic Del. Mary A. Marshall of Arlington, one of the 45 candidates running for nomination to the 18 Northern Virginia House seats covered by the primaries.

Many candidates complain that uncertainties over their campaign have handicapped them, making it difficult to raise funds or print campaign literature until the last few weeks. Those uncertainties, combined with the timing of the primaries between the end of the Labor Day weekend and the start of school, have done much to discourage voter interest.

Northern Virginia election officials say they expect about 10 percent of the 422,000 registered voters in the seven affected jurisdictions to cast ballots in the primaries. Polls will open at 6 a.m. Tuesday and close at 7 p.m. in Arlington, Fairfax, and Prince William counties, and Manassas, Manassas Park, Fairfax City and Falls Church. There are no primaries in Alexandria or Loudoun County, where candidates were picked by party officials.

Most interest in the region has focused on the Arlington Democratic Primary in which four incumbents are competing for the county's three available seats. Several women's political groups that had backed all four delegates in the past are now contributing money and aid only to Elise B. Heinz, whose Arlington-Alexandria floater seat has been abolished because of population losses in the inner suburbs. The other three Democratic incumbents -- Marshall, Warren G. Stambaugh and James Almand -- have been crying foul, claiming they too have championed the Equal Rights Amendment and deserve the support of the groups.

Sharp charges and countercharges also have been flying in northeast Fairfax County's 49th legislative district following complaints over a remark by GOP candidate Claiborne B. (Buck) Morton that "We'd be better off if only Christians were elected" to public office.

Morton, who first acknowledged making the comment but now denies it, says GOP Del. Martin H. Perper planted the information with the press because he was "scared I'm going to knock him out of his seat." Perper, meanwhile, is loudly denouncing a campaign letter circulated by Morton supporters that claims Perper supports "homosexual activists." Morton denies responsibility for the letter.

In southwest Fairfax County's 51st legislative district, GOP Del. James H. Dillard II, a social studies teacher, is lining up the support of county teachers to ward off an assault by ultraconservatives Robert L. Thoburn, who runs the Fairfax Christian School, and Lawrence D. Pratt, an incumbent and a registered Capitol Hill lobbyist for the Gun Owners of America.

Underlying all of the campaign activity seems to be a deepening commitment by area Republicans to seize more seats in the Democrat-controlled House of Delegates. Members of the GOP point with glee to Fairfax County's 50th district, where the Democrats could muster only two candidates for three available seats, as evidence of their newfound strength.

By contrast, the Republicans are running full candidate slates in all four Fairfax County House districts, and are also running primaries for the first time in Arlington and Prince William counties.

"Running as a Republican in Virginia is no longer a negative factor," says Eddie Stikes, executive director of the Virginia Republican Party, who says this year's crop of 29 GOP candidates is a record for Northern Virginia. "Ten years ago, it was almost suicidal to run as a Republican in some parts of the state," he said.

Fairfax County Democratic Chairman Dottie Schick insists that the party's failure to field three candidates in the 50th was caused by problems with "individuals -- not the party." Still, some Democrats say privately that recent population shifts, coupled with Ronald Reagan's popularity, could give the GOP a strong base for gains in the Nov. 3 election.

Traditional Democratic urban centers such as Arlington and Alexandria have suffered population losses during the past 10 years, shifting political power to Virginia's growing suburbs -- fertile ground for conservative Republicanism.

With all 19 Northern Virginia incumbents seeking reelection this year, some challengers grouse that the rushed election schedule puts them at a distinct disadvantage compared with officeholders who have longstanding organizations and better name recognition.

"Name identification is the most important thing in a voter's mind," said E. J. (Jay) Jarvis II, one of four Republicans running in the Arlington primary. "Someone who called and asked for their vote is going to be the one they choose. So I've got my little list and I'm making those calls."