In the 20 years that he was in the Virginia General Assembly, D. French Slaughter Jr. of Culpeper joined with the conservative Democrats who controlled the General Assembly on many issues. He supported segregated schools, the poll tax and sterilization for epileptics and retarded persons, and he opposed many civil and voting rights measures.

"I can't change my record and I wouldn't," says Slaughter, a 59-year-old Republican lawyer whose views are regarded by some as a throwback to an era when "massive resistance" to public school desegregation was the norm among Virginia politicans.

Most of those politicans either have changed their public views, suffered defeat or dropped out of politics altogether. Not Slaughter, who refuses to apologize for his votes or his past beliefs.

To the consternation of many Democrats, he has emerged as the front-runner in the race for the House of Representatives in the Virginia's largely rural 7th District, a wedge-shaped area that stretches from the West Virginia border to the Richmond suburbs. Polls conducted by Slaughter's Republican campaign and his Democratic opponent, Lewis M. Costello of Winchester, show him with a narrow lead in the race to fill the seat being vacated after 14 years by Republican Rep. J. Kenneth Robinson.

"Looking back, you can always see things that could have been done differently," Slaughter has said. "We were not always right, but we thought we were acting in the best interests of the commonwealth."

Slaughter, who was Culpeper's delegate to the Virginia House from 1958 to 1978, said in an interview that his views on voting rights remain essentially unchanged. He added that he always has favored the opportunity to vote for all Americans.

Speaking about the poll tax, which he supported as a requirement to vote in state elections after the tax had been ruled unconstitutional as a requirement to vote in federal elections, Slaughter said: "I saw no objection to it. It applied equally to all voters."

Asked if he regretted his votes favoring Virginia's policy of massive resistance to federally enforced racial desegregation of public schools in the early 1960s, he answered immediately: "No."

He added that he would not support either school segregation or the poll tax today because "it's no use to advocate legislation that has been overruled" by the courts.

Democrats insist that Slaughter's refusal to apologize for his votes, or even to declare that his opinions have changed, reflect his belief that voters in the conservative district will not hold those views against him.

"There are an awful lot of people in this district that supported the past that he espoused," said John J. (Butch) Davies III, Democratic Party chairman in the district.

"There are people who will identify themselves with" Slaughter's views, Davies added.

He said that while a "fringe element" still would support segregation, "there is a fairly significant part of the population that voted and participated in elections in the 1950s and '60s, and I think French will have some understanding listeners in that group."

Davies, along with other Democrats in the district, condemned Slaughter for his refusal to make a clear statement distancing himself from the his votes of two decades ago.

"In today's world, you cannot defend the poll tax," said Davies. "You can have no hesitation in condemning that."

"He's a reactionary," said state Sen. Thomas J. Michie Jr. (D-Charlottesville) about Slaughter. "I don't think the 7th District wants a reactionary like him at this time."

Slaughter, 59, who was regarded as a loyal lieutenant in the Byrd organization and was the chief sponsor of legislation creating the state's community college system, has allied himself closely with President Reagan, who is said to hold a 3-to-1 lead in the district, and with former senator Harry F. Byrd Jr. of Winchester, who endorsed him last week.

Slaughter was elected to the legislature as a Democrat and became an independent in 1972 when many conservatives deserted the state party after George McGovern was nominated for president.

As to whether times and attitudes have changed in Virginia, Slaughter said: "I think we should have equal opportunity for all Americans. The country's made a constructive change of course in the past four years and I support President Reagan."

Costello, 50, a Winchester tax attorney who never has held elective office, said that he does not want to engage in a "negative campaign" by attacking Slaughter on his legislative record. Democratic campaign officials say, however, they expect that Slaughter's record will be played up, through radio commercials and other media, despite Costello's reticence to attack his Republican opponent directly in speeches.

"My approach is not to discuss Slaughter's legislative record ," said Costello. "The media are developing that record. That's better than my doing it."

However, Costello's campaign began using a radio spot last week that attacks Slaughter's 1962 vote in favor of sterilizing unwed people who suffered from epilepsy, mental retardation and mental illness