The Virginia General Assembly, over the loud objections of its Republican members, today voted to join in a proposed "Super Southern" regional move to hold presidential primaries and nominating conventions during the same week in 1988.

The Democrat-controlled legislature also rolled over GOP opposition to approve a measure that would prevent the Republican-dominated Fairfax County Board of Supervisors from redrawing its supervisory districts until 1991.

The House of Delegates accepted, 57 to 41, the proposal requiring both of the state's major parties to hold their presidential nominating caucuses on the second Saturday in March 1988. The measure has passed the state Senate.

The regional move was initiated by Democrats who were dissatisfied with the delegate selection process in 1984 and irked that some presidential aspirants, such as John Glenn, had dropped out before several Southern states had had a chance to participate.

Political leaders, primarily Democrats, decided two months ago to hold primaries or caucuses on the second Tuesday in March 1988 or the following Saturday for states, such as Virginia, that traditionally hold the events on Saturday or have a conflict on Tuesday.

The measure provoked bitter opposition today from Virginia Republicans, who were left in disarray after devastating defeats in last fall's statewide elections. Several GOP legislators objected to their Democratic colleagues setting the 1988 Republican agenda.

"Here we go, meddling again," said Del. Vincent F. Callahan Jr. (R-Fairfax). "Let our own parties run their own events without undue governmental influence."

Under the bill, Virginia, which selects delegates through party nominating conventions, would participate in the regional move only if at least 10 other Southern states agree to join the nominating process.

Florida, Alabama and Georgia already have primaries on the second Tuesday in March. The Kentucky legislature has agreed to participate, and a bill is awaiting the governor's signature. Similar measures are pending in seven Southern states.

"It's important to the political process that the South have a major voice," said Del. Alan A. Diamonstein (D-Newport News), chairman of the Democratic National Committee's Southern Regional Caucus, which is meeting this weekend in Little Rock, Ark., to discuss the status of the Southern regional primary.

After another heated partisan debate, the House voted 63 to 35 to approve the controversial measure barring Fairfax County from realigning its supervisory districts until 1991. The bill has been approved by the Senate.

"It is specifically designed to not allow the Republican majority in Fairfax to redraw its lines," said Del. James H. Dillard II (R-Fairfax). "Most likely they would redraw them in a way to favor Republicans."

Fairfax officials say they have redrawn the county's political borders about every five years because of population growth in the huge suburban jurisdiction. However, that growth has left some supervisory districts with significantly larger numbers of residents than others, officials say.

Democrats have accused the Republicans of wanting to realign the districts now in an attempt to increase their 5-to-4 board majority.

Del. Mary A. Marshall (D-Arlington), who shepherded the bill through the House, told her colleagues that the measure is "justified to preserve continuity in government," a comment that drew snickers from the Republican side of the aisle.

Republican Fairfax County Board Chairman John F. Herrity has vowed to change the districts before the state law can take effect July 1. In a proposed schedule released yesterday, Herrity said the board would initiate redistricting proceedings at its meeting on Monday. Details of the plan would be made available to the public on March 7 and a public hearing would be held on April 21, with a final board vote set for April 28, he said.

Democratic legislators warned that the bill passed today requires that if Fairfax redraws its boundaries, it must hold any election based on those changes before July 1. Legislators said the board would be prohibited from doing so because it would cut short the terms of incumbents.