Alexandria Mayor James P. Moran Jr. (D) decisively upset Northern Virginia Rep. Stan Parris (R) in yesterday's election, combining caustic rhetoric and a well-financed, sophisticated campaign to unseat the six-term congressman.

Moran, who resurrected his political career from ashes only five years ago, overwhelmingly carried his Democratic home town and ran nearly even with Parris in Republican-leaning Fairfax and Prince William counties, breaking Parris's longtime dominance of the suburban part of the 8th Congressional District.

With 100 percent of the district's 154 precincts reporting, Moran had 52 percent of the vote and Parris 45 percent. Only two years ago, Parris won reelection with 62 percent of the vote. He had not had a close race since 1982.

In other races, Republican Sen. John W. Warner and Republican Reps. Frank Wolf of the 10th District and D. French Slaughter Jr. of the 7th District easily won reelection. Fairfax County Sheriff Carl Peed (R) and Arlington County Board member Mary Margaret Whipple (D) also won new terms. H. Roger Zurn Jr. (R) defeated incumbent Howard P. Smith (D) for a one-year term on the Loudoun County Board of Supervisors.

Two amendments to the state Constitution that would have enabled state and local governments to borrow up to $1.2 billion for transportation projects went down to overwhelming defeat.

Moran's victory removes from Congress one of the District of Columbia's strongest critics. Parris was ranking Republican on the House D.C. Committee and frequently delivered stinging public critiques of the District's crime and budget problems. Moran alleged during the campaign that Parris's attacks on the District were motivated by racial prejudice. Moran said he would not seek a seat on the District Committee.

Eleanor Holmes Norton, elected yesterday as the District's delegate to Congress, hailed Parris's defeat and exclaimed in her victory speech, "Thank you, Northern Virginia!"

The Moran-Parris campaign was one of the most strident and most expensive House contests in the country. Moran sharply attacked Parris for opposing abortion rights, capitalized on public disgust with Congress's performance in the federal budget crisis and once angrily called Parris "a deceitful, fatuous jerk."

Parris hammered at Moran's conviction on a conflict-of-interest charge in 1984, and stressed his own role in getting transportation improvements for the area and tending to the concerns of federal workers. But in October, the budget crisis created uncertainty for many federal workers, and even Parris's aides admitted that his popularity dropped sharply.

Moran also may have benefited from his support for abortion rights; last year, Virginia Gov. L. Douglas Wilder hurt his Republican rival in Northern Virginia by stressing the GOP candidate's opposition to abortion.

In his concession speech, Parris blamed the budget crisis for his defeat. Parris won his first House term in 1972 but was defeated two years later in a Democratic tidal wave that resulted from the Watergate scandal. He did not return to the House until 1980.

"In 1974, I got run over by a train called Watergate," Parris said, "and now it very much appears the same train 16 years later is going to run over me again.

"But let me tell you something. The good news is there is life after government."

Moran said he won because Parris had come to take his seat for granted. Moran stumped tirelessly for six months. Parris was tied up in budget debates for much of the fall, but aides in previous campaigns have said that Parris is sometimes a reluctant campaigner.

"Parris took it for granted, and he let it get away from him," Moran said. "He assumed he was a sinecure, that his seat was safe. We took it away from him."

Moran said last night that among the reasons he won were his confrontational style and his sometimes harsh stump rhetoric. Parris has long been noted for bluntness, and Moran said it was necessary to reply in kind.

Moran prepared for his campaign debates with Parris by jousting with state Sen. Joseph V. Gartlan Jr., a Democrat who impersonated Parris. Gartlan gleefully said last night, "I let him have it with both barrels."

Moran also criticized Parris's longtime political consultant, prominent Republican Charles Black, saying Black has overseen dirty campaigns nationwide. "If that's the way he's going to run his campaigns," Moran said of Black, "we're going to go out and beat him every time."

The 8th District was Northern Virginia's most closely watched campaign, with Parris and Moran waging a heavyweight political slugfest.

The district includes Alexandria and parts of three counties: southern Fairfax, eastern Prince William and northern Stafford.

Moran and Parris each expected to raise almost $900,000, making theirs one of the most costly House races in the country.

Moran made abortion the centerpiece of his challenge, attacking Parris for opposing abortion. He aired television commercials that showed women behind jail bars, saying that Parris once said he would imprison women who had abortions.

Parris denied the allegation and accused Moran of taking an extreme position on abortion.

Parris also emphasized Moran's conflict-of-interest conviction.

Moran resigned from the Alexandria City Council after he cast a vote that aided a developer with whom he had a business relationship.

Moran acknowledged that Parris's use of the conflict-of-interest conviction hurt his campaign, but said, "That's the only thing Parris had."

Late in the campaign, Moran contended that Parris had used "racist tactics" during his political career, and pointed a finger at Parris's criticism of the District. Moran said his campaign polls showed that many Northern Virginians previously had supported Parris because "he protects us from the District of Columbia," but Moran said he believes that strategy "no longer cuts."

In the 10th and 7th districts, Wolf and Slaughter began their races as overwhelming favorites, but both also were affected by late-breaking public restiveness with Congress.

Wolf, a five-term incumbent, represents Arlington, Loudoun and northern Fairfax counties.

MacKenzie Canter III, his Democratic opponent, had little money and was able to attract only limited attention, but tried to mount an anti-incumbent appeal. With 99 percent of precincts reporting, Wolf had 62 percent, Canter 34 percent.

Slaughter, a three-term incumbent, represents a sprawling district that includes western Prince William and Fauquier counties. He initially was expected to have no problem with Democrat David M. Smith, largely because of the district's overwhelmingly Republican sentiments.

But Smith mounted a well-financed, aggressive campaign, and Slaughter was criticized for lackluster performances on the stump. With 100 percent of the district's precincts reporting, Slaughter had 58 percent and Smith 42 percent.