With Virginia Gov. John N. Dalton and a packed house of Republican officials and campaign contributors looking on, former Fairfax legislator Wyatt Durrette announced his candidacy for state attorney general today.

Durrette, whose expected nomination for the same post in 1977 was derailed by a brash underdog named J. Marshall Coleman, is not likely to have any opposition within the party this time, as today's gathering indicates. hEvery major Virginia GOP figure already has endorsed his candidacy, and no Republican is expected to run against him.

"He's everybody's candidate," said Guy Farley, a Warrenton lawyer who plans to announce his own candidacy next mouth for lieutenant governor -- a contest expected to be far more spirited. "He's in an enviable position."

Durrette, 42, a Vienna lawyer who represented Fairfax County for six years in the state House of Delegates, has been campaigning ever since he lost the 1977 nomination to Coleman, who went on to become Virginia's first Republican attorey general. Durrette is known to have solid support from Republicans and Richmond's conservative "Main Street" businessmen, many of whom already consider him their choice for governor in 1985.

"To me there is no higher honor in public life in Virginia," he said today. "Surely I entertain that hope [of being elected governor] one day, but we take the one at a time."

Durrette's announcement speech did not deal extensively with issues. He said he would stress tougher criminal penalties and a revitalization of "federalism" in his campaign. He also said, to the applause of the crowd, that he opposed collective bargaining for public employes and repudiated a bill he cosponsored in the legislature six years ago that would have allowed localities to discuss salaries and working conditions with union groups.

Political consultant Edward S. DeBolt said he thought Durrette might need as much as $500,000 for his campaign. Asked where he would raise funds, Durrette looked around the room at his wealthy Republican backers and said: "Right here."