Fairfax County Supervisor Joseph Alexander, after a forceful and unusually public lobbying campaign, said yesterday he has failed to win appointment to the powerful Virginia State Highway Commission while maintaining his position as a director of Washington's Metro transit system.

Alexander said the at-large urban seat, which Northern Virginia has hoped to claim to increase its influence in state transportation decisions, is now likely to go once again to someone from the Tidewater area. A spokesman for Gov. Charles S. Robb said that no at-large commissioner has been selected.

The 10-member highway commission, traditionally the most powerful state board, with millions of construction dollars to award, lost three members because of conflict-of-interest charges last fall. Robb has selected but not announced commissioners to represent Northern Virginia and the Winchester area, and Alexander wanted the third, at-large, vacancy.

The five-term supervisor, one of the most durable Democratic politicians in Northern Virginia, had conducted an open campaign for the highway commission seat since Robb's election last fall, an unusual approach in a state where such politicking is more often conducted behind closed doors. Alexander's persistence and experience won him the support of the Democrats in the Northern Virginia delegation to the General Assembly and of the Fairfax and Arlington county governing boards.

Several of Alexander's backers privately questioned, however, whether he was the ideal candidate, given the other public jobs he holds. Some also said that Alexander's public display of interest had placed Robb in a difficult position, since he would have difficulty appointing someone else without embarrassing Alexander. "I think he's backed himself into a corner," one business leader said last month.

Yesterday Alexander moved himself out of the corner, although not without expressing some bitterness toward highway commissioner Harold C. King, who Alexander claimed cost him the seat. Alexander said Robb offered him the job Wednesday with no strings attached, but backed off Friday after King suggested that serving on both the highway and Metro boards might constitute a conflict of interest.

"This had been in the works for about the past two months, and there hadn't been any indication there was a problem," Alexander said. "This was at the eleventh hour."

Asked whether he believed King has sandbagged his nomination, Alexander said, "I wouldn't go quite that far."

Robb could not be reached for comment, but his spokesman said the governor agreed with both King and the state attorney general that serving on both boards could cause problems. "The governor felt it would be concentrating too much in one individual," the spokesman said.

King said yesterday he had mentioned to the governor's appointments team that the at-large urban commissioner also chairs a public transit committee, and he asked whether that might constitute a conflict for a Metro board member. But he said he has taken no interest in who is appointed.

"I've left all that up to the governor's office and the appointments people," King said. "Let me say I am very wary of any conflict of interest of any of our people, as I guess I should be expected to be."

T. Ray Hassell III, the former urban commissioner from the Tidewater region, resigned last year for what Gov. John N. Dalton said were technical violations of the conflict-of-interest law. It was later disclosed that Hassell voted to award thousands of dollars of contracts to a paver, later convicted of bid-rigging, with whom Hassell was involved in a development venture and that Hassell also lobbied for a state highway contract that benefited his engineering firm.

Northern Virginia commissioner William B. Wrench resigned in September after it was disclosed that he voted to locate a proposed highway near several business parcels he owns. Winchester commissioner H. Delmar Robinson resigned in December after it was disclosed that two businesses where he served as president and vice president had sold goods to the highway department.

Fairfax Sen. Adelard L. Brault, who along with other Northern Virginia Democrats urged Robb to appoint Alexander, said he was "very disappointed" Alexander decided not to resign from Metro, where he has served 12 years.

But Republican Del. Vincent Callahan said Alexander's position as supervisor could have led to charges of favoritism from other counties and that he would have been "serving two masters."

Alexander said he could have served all three constituencies fairly, but since he had to choose he would not abandon his current posts. "I cannot give up 12 years of work on the Metro Board," he said. "My commitment is to Fairfax County."