Democrat Andrew Miller's polls show that about 80 percent of Virginia's voters have already decided whom to vote for in the state's U.S. Senate race and that Miller holds a "comfortable" lead over Republican John Warner, Miller's campaign chairman said yesterday.

Allen Clobridge - questioned about the polls in an interview - said the unusually small percentage of undecided voters apparently reflects strong voter approval of Miller's record as Virginia attorney general and acquaintance with him through his three previous campaigns for statewide office.

"We are very confident that voters know Andy Miller and what they know about Andy they like," Clobridge said. He said the Miller poll showed many Virginians had also heard of Warner, but that most knew too little about him to register either approval or disapproval.

Clobridge was reluctant to talk much about the campaign's latest poll, which he said was conducted by Peter Hart and Associates shortly before the Labor Day weekend.

But he said the results had reinforced an earlier decision to run a positive, issue-oriented campaign designed to reinforce the image of Miller that voters already have.

"We are not running against John Warner but for the U.S. Senate," Clobridge said. He conceded that "if the situation changed we would probably change," but said, "We will not shoot 'attack media' (use paid ads attacking Warner) unless we know it's necessary."

Clobridge's remarks provide the first real glimpse of the strategy of the Miller campaign, which was as late as last month appeared drifting amid problems with staff and money.

Since then, he said, organization has taken hold and while money is still tight, "we're about where we want to be" with some $150,000 raised out of the projected $750,000 budget.

The biggest money problem, he said, has been caused by provisions of the 1974 federal campaign donations to $1,000 or less.

That, he said, "has reduced the pool of money," available for candidates to draw from and sent Miller all the way to Miami on Wednesday to a fundraiser with Miller-minded sympathizers there.

It has also, he said, complicated the cash flow situation in the state.

"There is a traditional pattern in this state," he said, "that local finance committees finance their own local activities, while the statewide operation and the media budget have been financed by large corporate checks."

Under the present law - which does not apply in state elections - there can be only one campaign committee. Local committees, he said, have a hard time understanding why they must sent all the money they raise to Richmond and then have it doled back to them.

Clobridge noted that the Miller campaign's August poll was taken before Labor Day. That was when Warner forces launched a saturation campaign of radio advertisements around the state featuring endorsements of Warner by Gov. John Dalton and former Gov. Mills Godwin.

Since then, Clobridge said, he would expect Warner's home identification to have risen significantly but not enough to signal any "erosion in the support that we have."

The poll showing him to be "comfortably ahead" in a race with relatively few undecided voters apparently has fortified Miller's decision to exclude Carter administration figures from his campaign and to give controversial former Lt. Gov. Henry E. Howell a strictly limited role, if any.

Some Democratic party officials and campaign workers have said in interviews that Miller should use Howell extensively to help stimulate a large turnout of black voters, labor and liberals that have regarded him as the champion of their causes in the state.

However, Clobridge said that no plans have yet been made for a Howell role. "I have a tentative meeting set up with him in Norfolk next Wednesday, but I don't know exactly what he will do," Clobridge said. "It is a tricky solution because there are people in this state who don't like Henry Howell at all and there are people who think he is the greatest person in the world and ought to be governor today."

Howell defeated Miller in the Democratic primary for governor last year, a race that created bitter feeling between the two men. Howell was then decively beaten in the general election by Dalton.

Howell has publicly endorsed Miller and said that he is willing to work for him, but he also has been quoted as saying that he wishes Miller would adopt more liberal positions on some issues.

While avoiding a conspicuous role for Howell, Miller has enlisted the active campaign aid of moderate-conservative Lt. Gov. Charles S. Robb, and is bringing into the state a parade of generally conservative Democratic U.S. senators to speak in his behalf.

Tr for add five

A planned appearance for West Virginia Sen. Robert C. Byrd in Winchester, where Virginia's conservative, independent Sen. Harry F. Byrd Jr. lives and owns the newspaper, raises intriguing possibilities for headlines announcing a "Byrd endorsement" there.

Harry Byrd is a member of the Democratic caucus in the Senate, but has remained aloof from party politics since he began running as an independent in 1970, a time when liberals were taking control of the Virginia Democratic Party.