Democratic members of the Virginia General Assembly, trying to end the party disunity that has contributed to recent defeats in statewide races, met here today and endorsed the Democratic candidates for governor, lieutenant governor and attorney general.

At the head of the ticket nominated in a June 14 primary and endorsed today is former Lt. Gov. Henry E. Howell a liberal-populist who ran twice for statewide office as an independent during the decade of party turbulence in which he played a central role.

When he was defeated in a 1969 Democratic gubernatorial primary, Howell was snubbed by party conservatives led by Gov. Mills E. Godwin and former Rep. Watkins Abbitt. He reacted by telling his supporters they were "free spirits" in the general election. With support of many moderate-liberal Democrats. Republican Linwood Holton in 1959 became the first member of his party elected governor of Virginia since Reconstruction.

Howell ran successfully as an independent for lieutenant governor in 1971, defeating a Democrat and a Republican and then in 1973 lost as an independent to Godwin, who ran for a second term as a Republican. The Democrats did not nominate a candidate in 1973.

Against the backdrop of this history, the endorsement of Howell by the generally moderate-conservative legislators attracted more attention than normally paid the blessing of a party slate by party officeholders.

The endorsement came in a jocular meeting of the House and Senate Democratic caucuses, where the potential for controversy apparently was partly dissipated by the presence on the ticket of moderate Charles S. Robb of McLean, the candidate for lieutenant governor, and conservative Richmond Del. Edward E. Lane, the candidate for attorney general.

During the years in which Howell was a leader of the party forces at war with the conservatives, Lane was a member of the conservative camp who remained a supporter of Godwin even after his switch to the Republican Party. Today, Lane said to the joint caucus, "There have been a lot of temptations to leave the Democratic Party, but I never have."

About half of the 113 Democrats who dominate the 140-members Assembly were present. Caucus leaders and Howell campaign aides said all but a few of the absent had sent letters of support for the ticket.

Only a few assembly members endorsed Howell before the party primary. Most remained publicly neutral or supported former Attorney General Andrew P. Miller, a moderate-conservative who lost to Howell by about 13,000 votes out of about 493.000 cast.

Miller was present today for his first public appearance with Howell since the primary and again pledged his support for the whole ticket. "I feel that it is terribly important that the state Democratic Party learn from the mistakes of the past," Miller told the joint caucus.

Howell called Miller "a strong man, a good man and a great Democrat." During the campaign, Howell called Miller the weakest of all opponents for statewide office and said he was unqualified to be governor.

The defeat of Miller has galvanized old foes of Howell, including some conservatives Democrats, behind the campaign of the Republican nominee Lt. Gov. John N. Dalton.

They organized last week as a group called Virginians for Dalton, headed by former Democratic Del. W. Roy Smith of Petersburg. Fire cochairmen of the group are former Rep. Abbitt of Appromattox, D. Lathan Mims, chairman of Independent Sen. Harry F. Bryd's 1976 campaign: Del. D. French Slaughter (I-Culpeper), a former Democratic member of the House; Lloyd Nolan, a Newport News businessman; and E. Massie Valentine, a Richmond insurance executive who served as chairman of Miller's statewide finance committee.