In a move Virginia Democratic leaders heraled as the first significant step toward party unification in more than a decade, members of the state central committee last weekend chose liberal Ira M. Lechner as the new party vice chairman for development and organization.

The choice of Lechner, an Arlingtonian who waged a surprisingly strong campaign for the lieutenant governor's nomination this spring, fulfilled a promise hammered out by state party officials on the eve of the state Democratic convention. The decision is viewed by many party leaders as an astute move by Lt. Gov. Charles S. Robb, the Democratic nominee for governor and a prime mover behind the decision last weekend, to win support of Northern Virginians and liberal Democrats, two groups traditionally not predisposed toward Robb. The move, Robb officials hope, will end a 12-year streak of gubernatorial losses for the Democrats.

"More than anything, the election of Ira is a pragmatic move," said Robert Lambeth, Democratic chairman in the conservative 6th Congressional District in southwest Virginia, who has been active in Democratic state politics for 14 years. "The party is tired of losing and I think that for the first time, we've come to realize that if we are going to win this one we need to include all factions and points of view."

The committee also elected Sen. Daniel Bird, of Wytheville, as vice chairman of finance, another newly created post. Several other top party posts were decided at the state convention -- Owen Pickett, a member of the state House of Delegates from Virginia Beach, was reelected chairman, while Jessie Rattley, a City Council member from Newport News, was elected first vice chairman, and W. Raymond Colley, of Alexandria, was selected as second vice chairman.

Lechner, a liberal maverick on the Virginia political scale and a former state delegate, heads a large constituency of activists from labor unions and consumer, feminist and teacher groups and is regarded both inside and outside the party structure as a top-notch political strategist. Those technical abilities, says University of Virginia political analyst Larry Sabato, probably resulted in the relative accord at last weekend's central committee meeting -- a marked contrast to the often rancorous debate at the state party convention -- and made Lechner's selection palatable to party conservatives.

Among Lechner's first duties will be a statewide voter registration drive, the first in the party since Lyndon Johnson's presidential campaign of 1964.

"Ira is known for his superb organizational abilities," said Sabato, "and is precisely what an underorganized state Democratic party needs."

Whether Lechner's troops will follow his lead, and to what extent they will work for Robb, has yet to be judged. Several delegates at the state convention, who had supported Lechner's campaign for the lieutenant governor's nomination, left the convention vowing to sit out the election. And even Lechner says his new role in the party, will not alone resolve some of the serious ideological problems that liberal Democrats have with Robb.

"I have never claimed to be a pied piper," Lechner said in an interview this week. "The whole essence of the people who relate to my candidacy is that they are independent people who make up their own minds. They are not soldiers that take orders from me.

"They will probably factor into their decision that I am working for Robb, but I have always felt they will vote for the ticket if it stands for what they believe in."

His acceptance of a top party position, Lechner said, should be viewed as more than a short-term drive to win an election. And, he added, liberals who are uncomfortable with his decision to embrace the party ticket should realize that the only way to effect change is to work within the party structure.

"What it says is that the liberals are not going to be blamed for sitting this one out," he said. "We've been called party wreckers for too long. . . . My goal is long term as well as short term. I want to get the party to move in the right direction and be more concerned about issues that affect people rather than the country club.

"If my election means getting liberals back into a position of power, it also means changing the party."