Groups of Northern Virginia Democrats have joined what appeared to be a growing drive to draft Lt. Gov. Richard J. Davis for the party's nomination tosucceed retiring U.S. Sen. Harry. F. Byard Jr.

More than half of Alexandria's 55 elected delegates to the state Democratic convention in Roanoke signed a telegram yesterday urging Davis to step into the void created by the sudden withdrawal of apparent nominee Owen B. Pickett and accept a draft. Similar efforts were under way in Fairfax County, which will send the largest county delegation to the June 4-5 nominating convention.

"It seems like Davis is the first choice of the delegation," said Alexandria Democratic party chairman Don Henry, one of the at least 30 delegates to sign the telegram.

Davis has been in Chicago most of this week, far away from the dramatic series of events that have rocked his party. The day after Pickett withdrew, state Sen. L. Douglas Wilder of Richmond said he would not make his threatened independent run for the Senate.

Robert Watson, Davis top aide, said yesterday he has received reports of unsolicited "draft Davis" efforts in the Shenandoah Valley, Southwestern Virginia and in Portsmouth, where Davis served as mayor. Davis has said he will be available for a draft and will assess his situation when he returns to the state this weekend.

No other candidate has made a move for the nomination. State Senate Majority Leader Hunter B. Andrews of Hampton is expected to confer with Davis over the weekend; Fairfax County prosecutor Robert F. Horan postponed what some expected to be an imminent announcement of his candidacy, and former state Attorney General Andrew P. Miller of Alexandria went on a trip to Alabama.

For many, Davis, the party's top votegetter in last year's state elections, remains the ideal choice. "I don't think we could find a better candidate, I don't think Virginia could find a better senator," said Alexandria Democrat Jared Cameron, who organized the telegram to Davis.

Others who signed the Alexandria telegram included Del. Marion Van Landingham, Mayor Charles Beatley and former state legislator Armistead Boothe who almost defeated Byrd in a 1966 Democratic primary.

Tom Blackburn Rodriquez, a member of the Fairfax County Central Committee, said yesterday that an informal sounding of Democratic opinion in the Lee District showed "a surprising degree of support" for Davis. Roland Winters, another Davis supporter, said about half of the 40 delegates and alternates surveyed in the Drainsville area said they favored drafting Davis.