James R. Tate, a conservative Republican seeking a vacant State Senate seat, and Sen. Adelard L. Brault, a veteran moderate Democrat in a tough race against a political newcomer, yesterday reported collecting, borrowing and spending the largest sums in Northern Virginia electoral races.

Tate, Brault and dozens of other candidates running for Virginia Senate and House of Delegates seats and county suepervisor boards reported thousands of dollars in campaign contributions with the approach of next Tuesday's elections.

Tate reported $19,456 in contributions and $18,113 in loans for a total of $37,569, of which he reported spending $26,769 in his race to succeed retiring Democrat Sen. Omer L. Hirst in Fairfax County.

That was more than three times the amount of his Democratic opponent, Richard L. Saslaw, who reported $11, 787 in gifts and $8,678 in expenditures.

Tate got his major contributions and loans from real estate and contracting interests. He reported a $5,000 loan from real estate businessman M. Lee Minnis of Centreville, a $2,149.68 contribution from Vienna insulation contractor Pat O'Donnell and an $1,000 gift and $1,620 loan from Fairfax home improvement contractor M. Elton Garner.

Brault, 70, majority leader of the Senate, who is fighting for his political life against conservative Republican challenger John M. Thoburn, 22, reported $32,739 in gifts and loans, of which he reported spending $16,695 and keeping $14,419 in reserve.

By contrast, Thoburn raised $12,055 and spent $13,486 and reported unpaid obligations of $6,208.

Brault received nearly $14,000 in contributions of more than $100, much of it from construction businessmen, real estate dealers, bankers, car dealers and drug store companies. His largest gift was $1,500 from Falls Church car dealer William H. Page. He also received $750 from the Virginia Bankers Association's Political Action Committee in Richmond and another $750 from Dart Drug in Landover, Md.

Thoburn's largest gift was $800 from the National Conservative Political Action Committee headquartered in Arlington.

The automobile dealers' committee was one of about a dozen "PACS" -- political action committees -- whose names appeared repeatedly among reports of gifts exceeding $100. Land developers' groups such as the Richmond-based Realtors PAC and the Associated Builders and Contractors of Northern Virginia gave $200 to $500 sums to legislative candidates from both parties. Developers are considered to be among the strongest and most effective of the lobbying groups in Richmond.

Teachers' groups such as the Fairfax Education Association's Fairfax PACE and the Virginia Education Association's Virginia PAC also contributed to a number of candidates, most of them Democrats. The teachers have been involved in a prolonged dispute over pay with the Fairfax County Board of Supervisors.

In the supervisors' races, surprisingly close financial totals were posted by Supervisors Chairman John F. Herrity (R) and his opponent, Democrat Vivian E. Watts. Herrity, considered by many the front-runner in the race, reported $26,398 in contributions and $24,399 in expenses, slightly more than Watts' $26,004 in gifts and $22,909 in spending.

Herrity outmatched Watts with 32 gifts of more than $100 to Watts's 15. He received more than $6,000 from automobile dealers, including $1,000 from Rosenthal Chevrolet in Arlington. Watts, who has championed pay increases for teachers, received most of her large contributions from labor groups, including $500 from the teachers' Fairfax PACE and $500 from the county firefighters' union.

In the race to succeed controversial retiring Fairfax County Sheriff James Swinson, a Republican, GOP Candidate M. Wayne Huggins has outmatched Democrat Kenneth R. Wilson nearly 2 to 1 in gifts. Huggins reported collecting $7,464 to $4,028 for Wilson who has tried to link Huggins to the outgoing sheriff, the subject of mismanagement allegations.

In the equally hot prosecutor's race in Arlington, GOP challenger Henry Hudson has raised $9,467, more than double the amount raised by Democratic incumbent William Burroughs, who reported $4,007 in gifts.

In the Arlington County Board race, Charles Rinker and Mary Margaret Whipple, independents running with Democratic backing, reported raising $23,142, outmatching incumbents Dorothy Grotos and Walter Frankland, independents with Republican backing, who reported $21,011 in combined gifts.