A political dogfight in Northern Virginia and a wave of public disgust with government are sending last-minute shudders through the Virginia Republican Party, as three senior GOP House members battle unexpectedly tough opponents in Tuesday's elections.

In one of the nastiest and highest-profile races in Virginia and the Washington area, GOP Rep. Stan Parris is waging a bitter struggle in the 8th District against Alexandria Mayor James P. Moran Jr., a Democrat. Their confrontation, which has produced a barrage of negative television commercials and personal insults, is considered close by both campaigns.

But two other Republicans, 7th District Rep. D. French Slaughter Jr., of Culpeper, and 1st District Rep. Herbert Bateman, of Newport News in the Tidewater area, have seen once-safe leads over largely unheralded Democrats shrink in recent weeks. Slaughter, whose district includes western Prince William and Fauquier counties, is facing David M. Smith, a Winchester minister. Bateman is opposed by a former television reporter, Andy Fox, of Hampton.

Political analysts say all three Democrats are benefiting from voter antagonism toward Congress and President Bush that was generated by the recent federal budget crisis. Two years ago, Bateman and Slaughter won by large margins and have served uneventful terms, but analysts say they are suffering from anti-incumbent sentiment. Smith and Fox are first-time candidates.

Parris also won by a big margin in 1988, but analysts say he has been scarred by a tough Moran challenge. The two are expected to spend a total of $1.8 million in one of the most expensive and shrill House campaigns in the country.

A national Republican strategist, who asked not to be identified, said GOP polls show Slaughter and Bateman fewer than 10 percentage points ahead of their Democratic opponents, and Parris leading Moran by fewer than 5 points. All three Republicans' leads fell dramatically during the lengthy budget stalemate that ended a week ago, the official said.

Though several Virginia political activists said they expect Bateman and Slaughter to pull out narrow victories, the Democratic threat has unnerved a state GOP organization whose power shriveled during the 1980s. Virginia has 10 House seats; none of the state's five House Democrats has major opposition. Should Republicans lose only one of the close races, Democrats would control the state's House delegation for the first time since 1966.

"What we are seeing nationally is pretty much a collapse of Republican {polling} numbers, and many more races are competitive than we thought would be," said Larry J. Sabato, a political scientist at the University of Virginia.

"Bateman and Slaughter are good examples. They haven't done anything wrong," Sabato said. "But Republicans are disillusioned because President Bush abandoned his no-new-taxes stand. And he allowed Democrats to spend weeks painting Republicans as the party of the privileged, alienating some swing voters. Together, this could add up to a nightmare for the GOP."

Not all Virginia Republicans appear to be in trouble. Sen. John W. Warner has no Democratic opponent because party leaders figured they had no chance of beating him. And in Northern Virginia's 10th Congressional District, Rep. Frank R. Wolf is considered a relatively safe bet against Democrat MacKenzie Canter III, whose low-budget campaign has had trouble garnering public attention.

In the 8th District, however, Moran and Parris have staged a high-profile slugfest. The district includes Alexandria and parts of three counties: southern Fairfax, eastern Prince William and northern Stafford.

Parris, 61, has repeatedly questioned Moran's ethics, pointing out that he was convicted of misdemeanor conflict of interest in 1984. Moran resigned from the Alexandria City Council after casting a vote that aided a developer with whom he had a business relationship. He also repaid the city for a trip to Europe during which he conducted personal business.

Moran has hammered at Parris's opposition to abortion rights and has accused Parris of using "racist tactics" during his political career, saying Parris's highly public attacks on the District of Columbia have racial undertones.

The two present sharply contrasting philosophies. Parris, a conservative, voted against every budget proposal before Congress this year, standing by a promise to oppose new taxes. Moran, a self-described "progressive," criticizes Parris's voting record on environmental issues. One environmental group ranked Parris among the bottom 12 members of Congress on the environment.

The 7th and 1st Congressional Districts differ geographically, but their congressional races are strikingly similar. The 7th sprawls across the Virginia Piedmont, encompassing Winchester, Charlottesville and Fredericksburg. The 1st borders the lower Chesapeake Bay and includes urban Hampton and Newport News as well as the rural Northern Neck.

Slaughter has had three terms in the House and Bateman, four; both are in their sixties and both are traditional conservatives with plodding styles on the stump. Both Smith and Fox are in their thirties, are comparatively liberal and have waged vigorous grass-roots campaigns.