A new Republican poll in Virginia shows the party's three statewide candidates trailing their Democratic rivals, with GOP nominee for governor Wyatt B. Durrette behind Democrat Gerald L. Baliles by13 percentage points, according to Republican campaign officials.

The three-day poll completed Thursday night was conducted for state Del. W.R. (Buster) O'Brien, the GOP candidate for attorney general. The poll showed him trailing Democrat Mary Sue Terry by5 percentage points, 36 percent to 31 percent. Terry, a state legislator from rural Patrick County, had been trailing slightly in previous Republican polls.

The new GOP poll showed Democratic state Sen. L. Douglas Wilder of Richmond, the party's nominee for lieutenant governor, leading34 percent to 31 percent over his GOP rival, state Sen. John H. Chichester of Stafford County.

The lead for Baliles over Durrette -- 43 percent to 30 percent -- comes after more than a week of intense campaigning by Durrette that included a visit by President Reagan in Arlington Oct. 9.

A Washington Post poll published that day and taken between Sept. 25 and Oct. 6 showed all three Democrats with commanding leads over the Republicans among individuals who said they were likely to vote. Baliles led Durrette by19 points, 50 percent to 31 percent. The poll was sharply disputed by Republicans. Durrette and other GOP leaders said that The Post polled too few Republicans in its sample of 2,056 registered voters.

The Post poll indicated that few voters had focused on the statewide races and that support for Durrette and Baliles was soft. A recent poll by the Richmond Times-Dispatch showed Baliles leading Durrette by 3 percentage points among registered voters, but by 14 percentage points among respondents who said they were likely to vote.

Don Harrison, Durrette's press secretary, declined to comment on the latest GOP poll.

"We just don't know any particulars of the new poll," Harrison said. "We're just holding to our own polls, which is a 3-point spread for Baliles ."

In another campaign development, the Baliles campaign said it has begun running a "contrast" or negative ad in the Northern Virginia television market in which the Democrats question whether Durrette has enough experience to be governor. The campaign commercial tells viewers that Durrette has not won an election since 1975, when he last represented Fairfax County in the state legislature.

Durrette has been running several negative ads on radio about Baliles, but a dispute within his campaign over the use of negative advertising has kept them off television, campaign officials said.