Although weakened by the loss of key legislative leadership positions, the 27 members of the Northern Virginia delegation have drawn up an optimistic shopping list for the 1980 session of the General Assembly which opens in Richmond next week.

Their premier task, legislators from Arlington, Alexandria and Fairfax agree, is to find new funds for the local share of Metro operating costs. Higher gasoline or sales taxes are seen as key sources for that money.

Other priorities include: reducing the amount of real estate taxes homeowners must pay; protecting tenants and condominium owners; providing state funds for localities that forgo annexation efforts, and renewing efforts to pass the Equal Rights Amendment.

Prince William and Loudoun legislators will seek laws to help manage the extensive population growth in their counties. Restrictions on home builders, additional state funds for waste management and changes in state building codes are among their most pressing concerns.

As always, money will be of primary importance, particularly during the 1980 session -- which will adopt the state budget for the next two years. Legislators in both the House and Senate say Northern Virginia representation on appropriation committees could be crucial if the region is to get an equitable share from the state's pocketbook.

"There's a tremendous jam-up to get on the Appropriations Committee," said Sen. Clive DuVal (D-Fairfax). "Half the Senate wants to get on it and there are only four vacancies."

Much of the concern results from the recent loss of key leadership positions in both the House and Senate. Last month, Sen. Adelard L. Brault, a Fairfax County Democrat, was ousted as Senate majority leader. Earlier, another Northern Virginian, Del. Mary A. Marshall of Arlington, was defeated in her bid to capture the Democratic caucus chairmanship. As a result, she also lost her position as caucus secretary. Sen. Omer Hirst (D-Fairfax) gave up the prestigious chairmanship of the privileges and elections committee when he retired last week.

Norther Virginia lost another key post two years ago when Del. James M. Thomson of Alexandria, the House majority leader, was defeated for reelection. He was believed to be in line to become speaker of the House.

Taken together, the losses have alarmed some local legislators.

"Four years ago we had majority leadership in both houses and chairmanship of privileges and elections committees in both," said Marshall. "I think they've put Northern Virginia on hold."

"Obviously the defeat of Sen. Brault is going to have some impact on Northern Virginia's clout," said Sen. Wiley Mitchell (R-Alexandria). "But I am not personally as apprehensive as some of my colleagues. No one in the Senate is going to run around and swing hatchets at each other."

A further weakening of Northern Virginia's legislative power could result from the number of freshmen among this year's delegation. Veteran legislators complain that the tendency of area voters to defeat incumbents has hurt their ability to deal effectively in an Assembly which rewards seniority with committee chairmanships.

"People keep complaining that we keep electing new people. What they're saying is we keep electing Republicans," said freshman Del. John S. Buckley (R-Fairfax), one of eight Republican delegates from Fairfax's 18th and 19th districts. The other two delegates are Democrats. "But remember, Republicans have a good in to the governor."

If there has been a loss in prestige and power in the Northern Virginia delegation, there has been no less pressure from constituents for legislation of local interest. Members have received shoppig lists from their city councils, county boards, teacher associations, school boards and citizen groups.

"Finding a stable and reliable source for Metro funding has to be at the top of the list," said Del. James Almand (D-Arlington). Last week Congress agreed to authorize $1.7 million for construction of the last 40 miles of Metro's 101 mile system. But that agreement was conditional upon pledges by local jurisdictions that they provide a "stable and reliable source" for their share of construction and operating costs.

Among the various proposals to accomplish that goal are a 4 percent increase in the gasoline tax and 1-cent increase in the sales tax.The gasoline tax increase would raise an estimated $10 million a year. The sales tax boost would be expected to bring in $40 million a year.

Another major issue local officials and citizen groups are concerned with is spiraling real estate assessments which have increased annually by more than 20 percent in some areas. Alexandria's Sen. Mitchell says he will propose a constitutional amendment to grant homeowners a homestead exemption on property taxes. Instead of specifying a flat dollar amount, Mitchell's amendment would make the homeowner's exemption equal to 10 percent of the fair market value of single family homes and condominiums.

That amendment is also supported by a number of local taxpayer alliances.

In Richmond last month, a coalition of taxpayer groups also urged the General Assembly to change the state constitution to allow Virginians to pass laws through initiative and referendum.

One issue that seems to have the support of all groups is the full funding of House bill 599, a package which Arlington Del. Marshall describes as "a treaty between the cities and surburbs."

The bill, which was passed last session and will be funded in this one, provides money to areas in exchange for their not trying to annex land in neighboring regions. In what has developed as a type of state revenue sharing for localities, Northern Virginia communities would get $213 million during the next 10 years. During the next two years, Arlington, for example, would collect approximately $7 million.

Local governing bodies have presented their delegations with their own legislative requests. Fairfax County's Board of Supervisors pared their list to seven items, while the Arlington County Board included 38 proposals in theirs.

In addition to preparing legislative packages, the school boards and administrators in Arlington, Alexandria and Falls Church have hired a legislative consultant, Doreen Williams, to go to Richmond to represent their particular interests. Fairfax County schools have their own "watchdogs" at the General Assembly.

Teacher associations in the area have drawn up their own legislative proposals. The most urgent of these would reinstitute some type of collective bargaining, which was prohibited by a recent state Supreme Court decision.

The success or failure of Northern Virginia's legislative proposals will greatly depend upon the cooperation of the full General Assembly. Some legislators fear that recent leadership defeats signal the strengthening of a traditional bias against this region by the rest of the state.

"On a close vote on something that might affect funding to Northern Virginia, the fact that we don't have any leadership positions could result in us getting shortchanged," said Almand.

Mitchell, however, thinks the pessimism is unwarranted.

"We sit here in fear and trembling that something is going to happen to us. I have found there is nothing more vindictive than a loser and nothing more magnanimous than a winner. And all the people down there are going to be winners."