When Virginia's Democratic Party faithful rallied in the biting cold of January for the inauguration of Gov. Charles Robb, the political talk was understandably heady. The Democrats had swept the top three state offices while maintaining their almost traditional dominance of both legislative houses. But as fast as the first General Assembly came and went, so did the party harmony that was supposed to live at least long enough for Robb to balance the party's old and new guards and anoint a candidate to win the U.S. Senate seat being vacated by Harry Byrd Jr.

Today the governor has his hands full: his favorite for the Senate race-- Owen Pickett--was thought to be the strongest consensus candidate to oppose Rep. Paul S. Trible, who has the Republican nomination all but sealed. But a number of Democrats, including some key black members, who weren't all that enchanted by Pickett in the first place, are maneuvering in ways that point up dramatically the fragility of Gov. Robb's coalition--and could cost the party dearly in the Senate race.

It is the very success of Robb and his ticket at the polls, in fact, that has led to this trouble. After all, when a party does win total control, intra-party jockeying takes on new seriousness. And when that control is in the hands of someone who has been talking change--as Robb has been doing increasingly since taking office, committing himself to "acting affirmatively" to accord women and blacks a more representative role in state government--expectations rise.

But so do the anxieties of old-line Democrats in the legislature, who still think of Northern Virginia as some sort of alien nation and have difficulty with any sudden shifts of influence. Thus, while Robb was finding new faces--young black and white men and women--for executive office jobs long held by grayer male retainers, the speaker of the house, A. L. Philpott, was stacking key committees with colleagues less inclined to welcome great progressive thrusts in the legislative branch. As a result, bills ranging from a Martin Luther King holiday measure to a ban on tax exemptions for segregated schools died, stirring up new divisions in the party.

The point man for the dissatisfaction is State Sen. L. Douglas Wilder, Virginia's leading black politician. Wilder has threatened to bolt the party and run as an independent for the Senate unless Democratic leaders can demonstrate a stronger commitment than they did in the legislature on issues he says are of importance to blacks.

Robb tried to arrange a "summit meeting" to make peace between Wilder and Philpott, but the speaker made a point of being unavailable. Add to that a reference by Philpott to black legislators as "boys"--as in "I've never had any problems with those boys, they understand the system"--and the cleavage widened, even though Philpott did apologize the next day.

So what about Senate hopeful Pickett? He opened his campaign by invoking the name of Byrd--which was not the best way to attract Virginia's black party leaders, who have vivid memories of the Byrd organization's fight for "massive resistance" to school desegregation. Then Pickett compounded his problems at a meeting of top Democrats and Robb, when the candidate was "given every opportunity" to renounce, modify or explain his comments but reportedly failed to address the subject.

That frosted Wilder still more and stirred others in the party (including other Democratic hopefuls who would like to capture the nomination from Pickett) to urge that Pickett release his pledged delegates to the nominating convention in Roanoke June 4 and 5. This Pickett has now done, which may not endanger his chances for the nomination, but which does point up the volatility of the situation Robb is dealing with.

Wilder isn't likely to return to the party fold empty-handed, and Philpott may or may not care. Pickett surely does and Robb as well--because without some accommodation soon, the Democrats' day in the sun last January will seem tropical in retrospect as the next campaigns roll on.