J. Marshall Coleman's Fairfax County political supporters this weekend doubled the number of telephone calls they make each day in their campaign to push Coleman as the Republican nominee for lieutenant governor of Virginia.

Just two weeks away from Fairfax County's April 2 mass meetings to select delegates for the state GOP convention, Coleman's campaign workers are not the only ones increasing their efforts in the area.

Northern Virginia has become the state's most heated battleground in the hard-fought Republican races for governor and lieutenant governor because of its huge block of delegates to the nominating convention and the number of local candidates who are vying for statewide office.

Fairfax County alone has one-fourth of the delegate votes needed to win nomination. The combination of Fairfax County's 526 delegate votes and the votes of Northern Virginia's nine other jurisdictions would give a candidate 916 -- or about half -- the 1,951 votes needed for nomination.

That could dramatically affect the campaign of gubernatorial candidate Rep. Stan Parris, who is leaning heavily on his home base of Northern Virginia to shore up his delegate-weak campaign against Wyatt B. Durrette, a Richmond attorney and former Fairfax legislator whose name is still on the door of a Fairfax City law firm.

Durrette, by his count, has 1,199 delegates.

"We've got to win and win big," said Parris campaign aide Richard B. Leggitt. "If you don't win your base, where do you win?" He noted, "It's going to be crucial for both campaigns . . . . If they [Durrette's campaign] want to try for a knockout punch, that'll be a good place to try for it."

Campaign observers in both Republican camps concede that a narrow victory for Parris in Northern Virginia could be the death knell to his campaign, while any sizable show of support for Durrette could assure him the nomination. Parris supporters contest Durrette's delegate count claim, saying he has only about 983 of the potential 3,900 delegates.

Parris says he has 437 delegates, while Durrette puts the Parris delegates at 186.

Local interest has been intensified by the number of home town candidates in the state races. In addition to Parris and Durrette, four of the five candidates for lieutenant governor have local ties, pitting hometown hopeful against hometown hopeful and diluting support considered vital to successful campaigns. None of the Democratic candidates for high state offices is from Northern Virginia.

Durrette is aided by the massive size of Fairfax County, which forces eight delegate selection meetings, one for each magisterial district. About half of those districts are in the 10th Congressional District of Republican Frank R. Wolf, who has endorsed Durrette. Parris represents the 8th Congressional District, which includes the rest of Fairfax.

The separate districts with their individual party organizations make it difficult for any candidate to claim a countywide victory, said county Supervisor Thomas M. Davis III, a Republican who is trying to turn out supporters for Durrette in the Mason District of central Fairfax. "Every district is completely different," Davis said.

To complicate matters, this is not a campaign of popular votes and media advertisements. It is a fight to target a select audience of party activists. The winners will be determined by a body count -- a matter of which candidate can turn out the most supporters at local mass meetings where delegates are selected for the state convention in Norfolk May 31 and June 1.

"You're asking a lot more of supporters," said Tim Gresham, campaign manager for Richard A. Viguerie, the nationally known conservative direct-mail master running for lieutenant governor. "You're not just asking them to spend 20 minutes at the polls to vote. You're asking them to spend three or four hours one night at a mass meeting and then to go to Norfolk for two days."

The complex delegate selection process adds to the confusion of determining which candidate is leading. There is no official vote count at the local meetings, only each candidate's figures.

For example, at Friday night's Loudoun County meeting, with 51 votes at stake, Durrette and Parris claimed victory. By the Parris count, Parris won 26 votes and Durrette received 22 with two votes uncommitted. But the Durrette tally gave Durrette 27 votes and Parris 16 and left eight votes uncommitted.

Four of the five candidates for the Republican nomination for lieutenant governor live in the northern part of the state -- former attorney general Coleman of McLean, Viguerie, also of McLean, state Sen. John Chichester of Fredericksburg and Washington lobbyist Maurice Dawkins of Springfield. The fifth candidate is state Del. A.R. (Pete) Giesen of Augusta County.

The lieutenant governor's campaign has strained local GOP organizations as it has become part of a national debate on party ideology. At one end of the spectrum is Viguerie, who has gained a national reputation as a leader of the GOP New Right but is making his first entry as a candidate for state office.

At the other is end is Coleman, a party maverick with statewide name recognition who is trying to establish a political base outside of the Richmond party regulars who have shunned him in the past.

In recent years, the conservative faction of the GOP has grown in Fairfax County, and it has gained control of the party organization, whose representatives will run most of the delegate meetings. County party chairman Ben K. Partin has endorsed Viguerie, who is supported by other leaders of the conservative wing of the party.

Campaign aides in both the gubernatorial camps said they may have little control over any large blocks of delegates turned out by Coleman or Viguerie. Those delegates would be "unknowns" in terms of their commitments in the gubernatorial campaign, potentially skewing carefully constructed vote counts by Parris and Durrette.