Audrey Moore was orating with increasing volume at last week's Fairfax Board of Supervisors meeting as her colleagues clamored to take the floor away.

Finally, fellow Democrat Sandra L. Duckworth could take it no more. "You've been talking all morning," she burst out, not without a little exaggeration.

The nine Fairfax supervisors have entered that testy season of electioneering, even though their quadrennial election is 11 months away. All the signs are there: Board sessions are marked increasingly by "grandstanding and long speeches," as Republican Marie Travesky said, while outside the board room they already are soliciting support, trading rumors and watching nervously for opponents.

"They're acting as political as I've ever seen them," one board member said of his fellow supervisors.

The nervousness is particularly obvious this year because, for the first time in recent history, every incumbent appears to be running for reelection. Those who are likely to be asking for another term include Republican Board Chairman John F. Herrity and Joseph Alexander, the elder statesman of the board, who was first elected in 1963.

The election will offer the Republicans, now on the short end of a 5-to-4 split on the board, a chance to capture a majority for the first time. James M. Scott, Travesky and Duckworth are generally thought to be facing the toughest reelection battles and two of them--Duckworth and Scott--are Democrats.

No matter which party wins control next year, however, the county is likely to continue in the generally conservative direction the current board has charted. In Fairfax, unlike Arlington, few issues are decided along party lines; moderate or conservative Democrats, like Alexander and Martha V. Pennino, often side with Republicans like Herrity and Nancy K. Falck on such issues as how to maintain a favorable climate in the county for attracting new business.

Herrity, who as chairman must run county-wide, is in solid shape despite his shoot-from-the-hip style that has turned some people off. "If he wants to run, he's unbeatable," one Democrat said. "People see him as honest, consistent and one of them."

Some Annandale Democrats last week were promoting former Rep. Herbert E. Harris II as a challenger, a prospect that would have delighted some reporters since Herrity and Harris have tangled before with consistently explosive results. But Harris, back in his Washington law office after an unsuccessful attempt to regain his seat last month from GOP Rep. Stanford E. Parris, laughed at the report and said he hadn't considered such a move.

That left Democrats for the moment with nothing better than the prospect of what one called a "sacrificial lamb," someone like Vivian Watts, who ran a losing but credible campaign in 1979 and then translated her name recognition into a winning race for the state legislature two years later.

Herrity's strength has left him with enough time for some district politics, according to several reports. He has talked with Delegate-elect Stephen Gordy about challenging Scott, and with Del. Frank Medico about challenging Duckworth. Both men are likely to opt for keeping their present jobs instead.

Herrity also has been in touch with Republican friends in his home base of Springfield about a primary challenge to Travesky, with whom Herrity has feuded for years despite a shared party affiliation.

Travesky has had perhaps the stormiest term of any supervisor, angering some citizens who say she doesn't consult with them enough. At times, she seems to stumble from one hornet's nest to another -- from proposed public housing projects to unpopular highway schemes.

"Marie is just embroiled in all the turmoil that a growing district like Springfield has," said one sympathetic Republican.

Democratic high school counselor Tom Giska, who ran for supervisor as an independent in 1975, has already announced he hopes to capitalize on the turmoil by running against Travesky, but many politicians expect her toughest challenge to come from the conservative wing of her own party -- perhaps from anti-public housing activist and lawyer John Betts. Travesky managed to unload Betts as a resident of her district during last year's redistricting but he is planning to move back to Springfield.

Some Democrats have asked Travesky to switch parties or run as an independent with their support, but Travesky said she plans to run as a Republican. "The threat of the New Right has mobilized more people than I can ever recall," she said, and she clearly hopes to make that "threat" the issue.

Meanwhile, supervisors ranging from 15-year veteran Pennino to first-termer Thomas M. Davis III appear to be in good shape, promising the return of many old faces next year. Davis, a Republican in a district with many Democrats, has managed to build considerable popularity while keeping one eye on higher office.

Noted one admiring Democrat, "Every Democrat who would ever . . . run against him, he's appointed to some board or commission."