When it comes to electing U.S. Senators from Virginia, it's been a bleak history for the Democratic Party:

1972: Incumbent Democrat William Spong lost to the GOP's William Scott, whose term in office was riddled with controversy over his competence. He didn't run again.

1976: Former Chief of Naval Operations Elmo Zumwalt sailed into Virginia politics, only to wreck against the solid incumbency of Harry F. Byrd Jr., an independent.

1978: John W. Warner, using his considerable fortune as well as the fame of actress Elizabeth Taylor, to whom he was married at the time, narrowly defeated Democrat Andrew P. Miller.

1982: A young Republican congressman from the Eastern Shore, Paul S. Trible, was elected to the Senate to replace Byrd, who retired. The Democrats stumbled around for a candidate and then wound up with one, Lt. Gov. Richard J. Davis, who really wanted to run for governor and said so.

1984: Warner again, this time sweeping to a landslide 70 percent victory over former Norfolk Del. Edythe C. Harrison, whose campaign was hobbled by her abrasive style and almost total lack of support in her party.

Given that kind of record, some say, it's not too early for the Democrats to start thinking about 1988 when Trible is up for reelection.

At least four potential candidates are being prominently mentioned by Democrats now, including Reps. Norman Sisisky and Frederick Boucher, Portsmouth psychiatrist and party activist Ronald Dozoretz, and former governor Charles S. Robb.

Some party leaders say there is an intriguing fifth potential candidate: veteran state legislator Richard M. Bagley, now Secretary of Commerce and Resources.

Bagley, 57, a wealthy businessman, has strong ties to various elements of the party and is a fiscal conservative with a socially progressive record as chairman of the House appropriations committee.

A former delegate from Hampton, Bagley also could challenge Trible for support in the first congressional district, an area that Trible represented in the House and one that gave him a strong boost in the 1982 election.

Bagley last year won the respect of party leaders when he agreed to abandon both his campaign for governor and plans to become party chairman, a job that went to Davis in a party-unifying move.

Sitting in his office across from the capitol recently, Bagley said that he has always wanted to be governor and that to run for the Senate would require a change "in a lifelong goal." But he would not rule out the possibility of a Senate race.

Some campaign strategists say Bagley would even benefit from his rough, "bulldog" face, which they say could be highlighted to offset the "Ken and Barbie" youthful looks of Trible, 39.

"I have not heard his name (as a potential candidate)," Trible said of Bagley. "I suspect there will be a long list of candidates."

Robb, who left office in January and is being mentioned as a potential candidate for president or vice president in 1988, "clearly would be our best candidate" for the Senate, said Robert "Bobby" Watson, executive director of the Democratic Party. "I've seen no indication from him or those around him that he would run," Watson said.

Watson said the other potential candidates, including Bagley, would give Trible a tough race.

Dozoretz, a fund-raiser for Gary Hart and strong supporter of former Lt. Gov. Davis, considered running against Warner in 1984, but decided the race was unwinnable. With his money, he could afford a first class campaign in 1988 even though he is a political unknown outside the party.

Boucher already is traveling around the state in an effort to broaden his base, largely limited to his coal-mining region in far Southwest Virginia.

Sisisky, like Boucher elected to the House in 1982, must run again this year. Sisisky, a former state senator, is a wealthy Pepsi Cola distributor and businessman. A political moderate-conservative, Sisisky also could afford to finance much of his own race if needed, party leaders say.

Trible has about $400,000 already sitting in his campaign war chest and said this week he's aware he's being targeted by the Democrats. But Trible said he would focus on helping out in this year's congressional races before turning to 1988.