Northern Virginia voters will choose a U.S. senator, three members of the House of Representatives and several local officeholders Tuesday in elections that are expected to be dominated by entrenched incumbents.

Republican Sen. John W. Warner leads a list of incumbents who hold commanding leads over their challengers in crucial areas such as name recognition and fund-raising. The Northern Virginia race considered most competitive pits Rep. Stan Parris, a Republican, against Alexandria Mayor James P. Moran Jr., a Democrat, in the 8th Congressional District.

Because most state and local elections in Virginia are held in odd-numbered years, no members of the legislature are on the ballot and only a few local offices will be filled. Fairfax County will hold a special election for sheriff, the first contested race for that job in 10 years.

Also on the ballot are several local bond issues and state constitutional amendments, including one that would allow the state government to sell a new form of bonds, called pledge bonds, to finance transportation improvements. Gov. L. Douglas Wilder is campaigning for that proposal, saying failure to approve it would cripple efforts to improve Northern Virginia's road system.

"Clearly, the lack of strong challengers in many races is attributable to the power of incumbency," said Mark J. Rozell, a political scientist at Mary Washington College and a Vienna resident. Northern Virginia politicians "use the powers of incumbency well . . . . The name of the game in politics is survival."

In the only statewide race on the ballot, Warner is seeking a third term in the Senate. He is considered such a favorite that Democrats declined to nominate a candidate for the post. His only opponent is independent Nancy B. Spannaus, of Loudoun County, a supporter of jailed political extremist Lyndon LaRouche.

Beginning last year, Warner raised a million-dollar campaign treasury in anticipation of a tough challenge by Democrats. But the man considered his most formidable potential opponent, former governor Gerald L. Baliles, decided not to run, and party officials actively discouraged potential candidates who were considered long shots. In his last election six years ago, Warner trounced little-known Norfolk Democrat Edythe C. Harrison by a margin of almost 2 to 1.

Warner has campaigned only sparsely in recent weeks and has not acknowledged Spannaus at all. Spannaus has raised little money and has established only a minimal public profile for her campaign. Spannaus's husband was among several LaRouche associates convicted of fraud for their participation in a LaRouche fund-raising scheme.

Among the region's three contests for the House of Representatives, the most heated involves Parris and Moran. They are vying to represent the 8th District, which includes Alexandria, southern Fairfax County, eastern Prince William County and northern Stafford County.

Parris, who is seeking his seventh two-year term, is considered the favorite, but Moran has raised one of the largest campaign treasuries among congressional challengers nationwide.

So far, their race has focused primarily on abortion rights, which Moran supports and Parris opposes. Moran has accused Parris of a cynical flip-flop on the issue, saying Parris took a hard-line antiabortion stance during the Republican gubernatorial race last year but moderated his views somewhat this year. Parris acknowledges that his position has changed, but says Moran's support for abortion rights is extreme.

Moran and Parris also turned a debate on U.S. policy in the Persian Gulf into the region's most vitriolic campaign exchange. Several weeks ago, Parris compared Moran to Libyan strongman Moammar Gadhafi; Moran angrily said he would like to punch Parris in the nose.

In the 10th House District, which includes Arlington, Loudoun and northern Fairfax counties, Rep. Frank Wolf, a Republican, is seeking a sixth term; he is being challenged by Democrat N. MacKenzie Canter III, a lawyer. Canter has portrayed Wolf as too conservative for his district and has questioned Wolf's use of incumbent perquisites, such as free mailings.

But Wolf has raised far more money and is better known than Canter, who has never held public office. Wolf is also known for his attention to constituent groups, such as federal workers.

In the 7th District -- a large slice of central Virginia that includes western Prince William and Fauquier counties -- Rep. D. French Slaughter Jr., a Republican, is being challenged by Democrat David M. Smith, a minister and solar energy contractor. Smith has attacked Slaughter for opposing abortion and pointed to an article in a Capitol Hill newspaper that called Slaughter the "most obscure" member of Congress.

But the 7th District is overwhelmingly Republican and conservative, factors that weigh heavily toward Slaughter. Smith has never held elective office and is not well known outside his home area of Winchester.

In local elections, Fairfax County Sheriff Carl Peed, a Republican who was appointed to the job in February, faces Democrat Richard Singleton, a former Maryland prison warden, and independent Clarence A. Robinson Sr., a Northern Virginia minister.

The three are vying to finish the unexpired term of former sheriff M. Wayne Huggins, who resigned in February to become director of the National Institute of Corrections. The winner's term will expire next year.

Also in Fairfax County, four people are running in the nonpartisan race for three positions as Soil and Water Conservation District directors. They are A. Dewey Bond, of Great Falls; Gloria T. Fisher, of the Alexandria area; David C. Ray, of Annandale; and R.G. "Dick" Terwilliger, of Falls Church.

In Arlington County, two-term County Board member Mary Margaret Whipple, a Democrat, is being challenged by A.M. "Monte" Davis, a bank officer who is backed by county Republicans. Whipple is well known and Arlington is heavily Democratic. But Davis got 45 percent of the vote in an unsuccessful County Board campaign in May.

In Loudoun County, Supervisor Howard P. Smith, a Democrat, is contending with Republican H. Robert Zurn Jr. to complete the unexpired term of Alice G. Bird in the Sterling District seat on the Board of Supervisors. The winner will serve through next year.

Also in Loudoun, voters will decide whether to legalize betting on horse races, thus clearing the way for a privately operated racetrack in the county, and whether the chairman of the county Board of Supervisors should be elected by voters countywide.

The ballot includes four potential amendments to the state Constitution. If passed they would:

Allow the state to sell a new form of bonds to finance transportation improvements.

Allow local governments to sell similar bonds for transportation improvements.

Allow local governments to give real estate tax breaks to the disabled and senior citizens.

Allow the state to use money and property seized in drug raids to pay the expenses of police and law enforcement agencies.

Several local bond issues are also on the ballot. If approved they would:

Allow Fairfax County to raise $169.26 million for school construction; $80 million for transportation improvements; $9.5 million for human services facilities; $21.75 million for housing; $4.57 million for public safety facilities; $8 million for trails and sidewalks; and $6.72 million for storm drainage.

Allow Arlington County to raise $53.85 million for a new courthouse and police station; $23 million for school construction; $10.93 million for road construction; $4.22 million for parks; $2.5 million for a new fire station.

Allow Prince William County to raise $43 million to widen Davis Ford Road and to raise $970,000 to purchase a private water and sewer system in the county.

Allow Loudoun County to raise $11.285 million to improve its landfill.