For 10 years, Northern Virginia's state legislators have complained that they were robbed by Norfolk area lawmakers when the Virginia General Assembly last redrew the commonwealth's political map.

Today, on the eve of what will be the first state legislative session in the nation to deal with the results of the 1980 census, the Northern Virginians believe they may have finally got their downstate colleagues to recognize their clout. If all goes as a committee has recommended, the legislators from the Washington suburbs may be able to walk away from the State Capitol on Friday with three more seats in the House of Delegates than they had on Monday.

But as the 19 House members from Northern Virginia readily acknowledged last week, the battle for those seats is only half over. Having weathered the scrutiny of a House subcommittee. the Northern Virginian plan must get past 121 legislators who are as worried about saving their own political skins as the Northern Virginians.

"They are all as jumpy as cats," says Del. Elise B. Heinz, a Democrat who stands to lose her Arlington-Alexandria seat as a result of declining population in the inner Washington suburbs. Heinz, like most of the legislators, is apprehensive about the session for one reason: "It's not psychologically possible . . . to look at redistricting [without worring about] the problems of running for reelection in a month or two in a rearranged district."

Already, a number of Democrats in Southwest Virginia are plotting to undercut the delicate subcommittee plan that grants Northern Virginia three more seats for its fast-growing outer suburbs at the expense of two southwest Democrats, including House Finance Committee Chairman Archibald A. Campbell (D-Wythe), who has been in the legislature for eight terms. "We're going to fight it any way we can," said one. "Maybe I'll bite them [the plan's supporters] on the knee."

Although sectional rivalries have long played a role in Virginia politics, the reapportionment seesion will test them, along with the partisanship of the state's Democratic Party. The party, which this year will be seeking to regain the governor's office it last won in 1965, could rebuke Republican Gov. John N. Dalton by overriding any of the 29 bills he vetoed after the assembly's 39-day session earlier this year.

The assembly never has overridden a governor in modern times and many top Democrats say it's unlikely that they can muster enough votes to do it in this week's special session either.

Backers of the three votoed bills that attracted the most attention -- measures establishing a state holiday honoring Dr. Martin Luther King Jr. and funding abortions in cases of rape, incest and fetal deformity -- have said they doubt they can muster the necessary two-thirds votes in both houses to override.

The King holiday bill is backed by Lt. Gov. Charles S. Robb of McLean, the Democratic candidate for governor, and opposed by Attorney General J. Marshall Coleman, the Republican candidate. Despite the 3-to-1 Democratic edge in the assembly, threre are enough conservative Democrats who support Dalton's view against setting a holiday for the slain civil rights leader to make an override unlikely.

Generally, there is little partisanship in the Assembly, except at election time, and even the Democrats run unopposed in many sections of the state, despite the GOP's success at statewide elections.

"No one -- no one is looking out for the interests of the Democratic Party here, and it [the legislature] is their last bastion," says Larry Sabato, political science professor at the University of Virginia. "Maybe they think the General Assembly is impregnable. Or maybe they don't see competition coming from the Republicans. But it is."

The census results on which the reapportioning will be based will accelerate the rising power of the state's suburbs, regions that have been the bedrock for the growing Republican Party, Sabato notes.

Nonetheless, there has been some partisan maneuvering. Plans by the Democratically dominated Senate Privileges and Elections Committee would put State Sen. Eva Scott (R-Amelia), who defeated a popular Democrat, in a district that runs, in the words of one lawmaker, from "Florida to Maine."

The panel also has proposed that Republican Rep. Stanford Parris' Northern Virginia district be redrawn to exclude some of the conservative precincts that supplied his narrow margin over Democrat Herbert E. Harris II last fall.

Nor are the state's black voting groups happy over the prospects of the reapportioning. Population losses in Richmond and Norfolk could cost the seats of at least one of the House's four black members.

Whatever the legislators decide must be reviewed by Dalton, the Justice Department, which reviews all voting actions in the state under the Voting Rights Act, and possibly by the courts.

"There are those who may propose plans that won't be upheld by the courts, so that we could hold our elections under our present plan," says Del. Mary Marshall (D-Arlington)."That way they keep their seats for another session."