Time, and a little success, can change things.

Take Saturday night at the Democrats' annual Jefferson-Jackson Day Dinner. There was Virginia Lt. Gov. L. Douglas Wilder, standing before 1,000 cheering Democrats, praising the unity of the party and urging the election of Virginia Beach state Del. Owen B. Pickett to Congress.

Lusty cheers showed that the significance of Wilder's endorsement was not lost on party regulars. They witnessed that bitter political winter of 1982 when Wilder, then a state senator, almost single-handedly derailed Pickett's front-running campaign for the U.S. Senate.

At the time, Wilder said that Pickett, a conservative lawyer, had too warmly embraced Virginia's Sen. Harry F. Byrd Jr., and by inference, some charged, the Byrd organization's racist past. Wilder threatened to run as an independent.

Such a move almost certainly would have drawn thousands of black votes from Democrat Pickett. Within days, Pickett's campaign crumbled and Wilder returned to the fold as the Democrats settled on another candidate.

"They have made peace," one party operative said of Pickett and Wilder, whose feud was so intense and so well known that Republicans last year ran TV ads reminding voters of it in an unsuccessful attempt to split the Democrats and defeat Wilder in the Nov. 5 elections. The ploy failed.

Pickett, who was urged to run for lieutenant governor against Wilder in revenge last year, stayed out of that race. He endorsed Wilder and kept a lid on any personal feelings over the '82 incident.

It's paying off this year.

Pickett has emerged as the formidable consensus Democratic candidate this year for the 2nd Congressional District, which includes the cities of Virginia Beach and Norfolk.

As a team player, Pickett has won the backing of Levi E. Willis, the undisputed coalition leader among blacks in Norfolk, as well as backing from many other leaders, black and white, in Norfolk. Willis, Wilder and Pickett also sat together at the head table earlier this year when Wilder held his own fundraiser in Richmond.

The solid Democratic base in Norfolk is bad news for the GOP and its likely candidate, state Sen. A. Joe Canada Jr. of Virginia Beach, in the race to succeed veteran Republican Rep. G. William Whitehurst, who is retiring.

Pickett and Canada would be likely to split the big Virginia Beach vote, but Canada, also a Virginia Beach lawyer, has far less of a base in Norfolk.

The Pickett-Wilder patch-up could be bad news for the state GOP also. It's another sign that the party, spurred by the successes of former governor Charles S. Robb, indeed likes winning. Now it's the Republican Party that is trying to find a way to stem factional warfare.

"There's joy to be found in politics when you pull together," Gov. Gerald L. Baliles told the J-J celebrants at the Marriott Hotel.

Wilder also hailed the begining of one of the Democrats' toughest races this year, singling out Arlington County Board Member John L. Milliken.

Milliken is scheduled to announce Saturday his campaign against incumbent GOP Rep. Frank R. Wolf in the 10th District. The Northern Virginia race is shaping up to be a costly battle, but Democrats say the easygoing veteran board member is their best candidate ever against Wolf. Robb is hosting a $250 per person preannouncement fund-raiser at his McLean home for Milliken Friday night and is expected to campaign for him.

The keynote speaker at the J-J Dinner was Sen. Joseph Biden (D-Del.), who's busy exploring a run for president.

It was clear the dinner was Robb territory, even though the former governor continues to be tight-lipped about his political plans to play a national role in 1988.

Biden began his speech with a standard greeting to top party and elected officials, including Robb, who was not there. "President Robb . . . wherever you are in New Hampshire."

"I want you to know, Robb-Biden sounds great to me," he joked.

Baliles quipped that Virginia Democrats "are just 'Biden' their time."

Biden's long speech began humorously but turned serious and, some said, a little preachy. He said national Democrats can learn from the success in Virginia. He said the national party went awry in the 1970s and early 1980s because of "paralyzing self-satisfaction" of its successes from the New Deal to the 1960s.

"We forgot we had to constantly move on" with new ideas, he said.