The Democratic candidate for governor of Virginia, Gerald L. Baliles, and his two running mates have taken commanding leads over their Republican opponents in the state's Nov. 5 election, according to a Washington Post poll. It shows Baliles with a 19 percentage point lead over the GOP's Wyatt B. Durrette.

The poll of 2,056 registered voters shows Democrats leading in all sections of the state and across nearly all economic, social and political lines. It also shows support for both the Democrats and the Republicans to be soft, with many of those surveyed expressing indifference and little knowledge of the candidates.

The Democrats appeared to be benefiting from Gov. Charles S. Robb's efforts to recast their party in a more moderate image. It also appears that they will benefit from what is expected to be a large turnout of black voters and from apparent apathy among many whites and Republicans.

The findings come on the eve of President Reagan's first visit to the state this year. He is to address a fund-raising luncheon for the GOP ticket in Crystal City today. Durrette's advisers said the visit should be a boost to his campaign, which has been hampered by staff disputes over strategy and fund raising.

At this stage, the poll indicates that blacks will make up about 20 percent of the Virginia electorate -- sharply higher than in the past. But even if blacks make up about 14 percent of the voters -- their approximate proportion four years ago -- the poll shows Baliles still leads Durrette by as much as 15 percentage points.

Potentially as significant for the Democrats, the new poll shows Baliles leading among whites, 44 percent to 36 percent. No Democratic candidate has won a majority of white votes in a Virginia gubernatorial contest since 1965.

The polling, begun Sept. 26 and completed Sunday, showed Democratic state Sen. L. Douglas Wilder of Richmond, the first black to be nominated for a statewide office by a major party in Virginia, with a 48 percent to 26 percent lead in his race for lieutenant governor against Republican state Sen. John H. Chichester of Stafford County.

Wilder's margin was greater than Baliles', who led Durrette by 50 percent to 31 percent with 19 percent undecided. Wilder also is leading Chichester among whites, by 39 percent to 32 percent.

Democratic state Del. Mary Sue Terry of Patrick County, seeking to become the first woman in Virginia to be elected statewide, leads GOP Del. W.R. (Buster) O'Brien of Virginia Beach 43 percent to 27 percent with 30 percent undecided in the race for state attorney general, according to the poll.

The Post poll's findings show a much stronger lead for the Democrats than has any poll published in the state. A Richmond Times-Dispatch poll published Sunday showed Baliles with a 14 percent lead among people with a strong interest in the race. Baliles said yesterday the Post poll "tends to confirm private polls" that the Democrats have conducted.

"We think it'll get narrower," said David Doak of Washington, a Baliles consultant. "It'll be a dogfight, but [the poll] is good news for us."

A spokesman for Durrette said that "he doesn't have any faith in The Washington Post poll." Edward DeBolt of Arlington, Durrette's political consultant, dismissed the Post poll as "ridiculous . . . . Like in so many things, The Post is not right, and this is a good example . . . . What you've done is weigh the poll not the way [the electorate] is but the way you expect that it is."

The Post's findings, which have a margin of error of 3 percentage points, are based on an expected "probable electorate," in which some people's voting plans count more than others, based on their voting history and expressions of intent and interest in the 1985 campaign. The Post used this method in 1977 and 1981 gubernatorial preelection surveys in Virginia.

DeBolt said his polling shows Durrette, 47, a Richmond lawyer and former Fairfax County legislator, with a 3 percentage point lead over Baliles, 45, who resigned as state attorney general to run for governor. DeBolt acknowledged that Durrette's campaign has trailed Baliles' in effectiveness.

Baliles "has done a good job of firming up his liberal and moderate base. We, in contrast, have not done as good a job of getting word [about Durrette] out" to voters who typically vote Republican, DeBolt said.

The brightest findings for Republicans appeared to be that overall support for each of the candidates was weak, with a large number of respondents saying they knew too little about the candidates to form a strong opinion of them. The proportion of undecided voters in the governor's race -- 19 percent -- was also relatively high for an election that is only 28 days away.

In the 1981 race between Robb, who was the first Democrat to win the governor's office in 12 years, and Republican J. Marshall Coleman, only 9 percent of the voters were undecided in a Post poll taken in late September of that year.

Of voters preferring Baliles in the poll, 40 percent said they were "absolutely certain" to vote for him, compared with 10 percent who said they were uncertain. For Durrette, only 22 percent who said they favored him were "absolutely certain" that they would vote for him. Nine percent were uncertain.

Baliles, who upset Lt. Gov. Richard J. Davis of Portsmouth to win the Democratic nomination in the spring, has led what some say is a purposely low-key campaign that has stressed his ties to Robb, who cannot succeed himself under Virginia law. At the same time, the Democrats have gained considerable attention by having the first black and first woman on a state ticket.

The Post poll shows that about 30 percent of those interviewed believe that race and gender will hurt Wilder and Terry. About 10 percent said Wilder's race will help him win support. Only about 4 to 7 percent of the respondents suggested that as individuals they would be likely to vote for or against a candidate because of race or gender, with a large majority saying it would make no difference.

The poll showed that all six statewide candidates were so little known that many of those surveyed did not have either a favorable or unfavorable impression of them.

Thirty-one percent of those surveyed had a favorable opinion of Baliles and 14 percent were unfavorable, but 55 percent said they did not know enough about him to have an opinion. Sixty percent had no opinion of Durrette, while 24 percent had a favorable impression and 16 percent had an unfavorable one.

By comparison, Robb had a favorable rating of 73 percent and 12 percent unfavorable, and Reagan had ratings of 68 percent favorable and 26 percent unfavorable.

Some Republicans said Durrette has failed to establish his identity, giving a larger-than-necessary role to old-line, Byrd conservatives such as former governor Mills E. Godwin. Durrette yesterday picked up the expected endorsement of former U.S. senator Harry F. Byrd Jr. of Winchester, who said Baliles is too close to Wilder.

Wilder, a veteran of 15 years in the state Senate, led Chichester among blacks, 78 percent to 7 percent. Chichester, who at the outset of the campaign had been expected to defeat Wilder easily, trailed the Democrat even among white, "born-again" Christians. Wilder, whom Chichester has characterized as a liberal, led among that group 39 percent to 31 percent.

Fully six in 10 respondents did not know that Terry was a woman seeking the attorney general's office.

Terry's ratings were 22 percent favorable and 9 percent unfavorable, and 69 percent said they did not know enough about her to comment. O'Brien had a 15 percent favorable rating and 10 percent unfavorable, and 75 percent did not know him.