With less than a week left in Virginia's raucous lieutenant governor's election campaigns, the outcome of the race between Democrat Richard J. Davis and Republican state Sen. Nathan H. Miller seems to hinge on the play of one wild card: the conflict-of-interest allegations surrounding Miller.

But the question is which candidate will be helped -- or hurt -- by that issue. Some Republicans worry that the accusations have ruined Miller's chances for election. "It's devastating to the boy," said state Sen. Ray L. Garland (R-Roanoke), a top Miller adviser. "If Nathan Miller can win, he ought to go into the business of healing people -- he'd certainly be in demand."

Others in the GOP say the flap may have helped Miller by pulling Republican workers together and generating a sympathetic backlash for him.

And Davis strategists fear the widely publicized charges may actually win Miller votes on Nov. 3 from voters who can't remember why they recognize his name. "I'm just constantly amazed that it's still a horse race, but it is," says Joe Lockhart, Davis' press secretary. " . . . The message just isn't getting across."

Davis has pounded at the conflict charges against Miller and this week called for him to withdraw from the race, the most recent development in a fiercely fought battle between the little-known candidates. The two camps once jousted with amiable civility, but are now relying heavily on the kind of negative campaigning that has characterized this year's gubernatorial race.

The race between the boyish Miller, 38, a Shenandoah Valley conservative, and Davis, a 60-year-old liberal businessman from Tidewater, is the only one of this year's three statewide races that offers voters two widely different choices. Miller spent the last 10 years in the state legislature, and has supported Republican Presidents Nixon, Ford and Reagan. Davis, who won acclaim as Portsmouth's mayor for helping rebuild the decaying city, supported Democrats George McGovern and Jimmy Carter and Virginia's former gubernatorial candidate Henry E. Howell.

Democrats say their most recent telephone survey by pollster Peter Hart this week found that more than half of those who could identify Miller viewed him negatively. Republicans countered yesterday with a Richard Wirthlin poll that showed Miller leading Davis by 2 percentage points as of Sunday evening.

"It doesn't mean one hell of a lot in his favor, but it didn't show he had suffered a body blow as a result of the conflict controversy," says Republican Party spokesman Neal Cotiaux.

Both sides agree that they must win a large share of the race's undecided voters, who have accounted for up to 40 percent of the electorate in recent polls. For Miller, that has meant appearing with President Ronald Reagan and former governor Mills E. Godwin at a Richmond fund-raising event earlier this week in hopes that their popularity would rub off on him.

Miller won more enthusiastic applause than any other Virginia politician that night with a fiery pledge to battle the conflict-of-interest allegations: "I shall fight. If I have to fight them one at a time, I will. If I have to fight them all at the same time, I will."

Davis is campaigning hard in Northern Virginia, where the conflict charges have been the dominant issue, and his strategists believe he can pick up Republicans disillusioned with Miller. "We just have to remain as visible as possible and remind people what's gone on," says Lockhart.

The conflict charges against Miller first surfaced last August, with published reports that Miller's law firm had received more than $250,000 in legal fees from his clients, the state's electrical cooperatives, while Miller was drafting and voting for legislation that gave the co-ops $13.2 million in tax breaks and business advantages. Last week, it was reported that Miller had introduced and helped secure passage of laws designed to help another client in obtaining valuable mineral rights.

Privately, several state Republican officials say they share Democratic gubernatorial candidate Charles S. Robb's view that Miller's actions were "indefensible." But they say that this year's race, which will determine whether Virginia Republicans can continue their 12-year reign in the governor's mansion, is too crucial for them to defect in the last days of the campaign.

"There is simply too much at stake and people in the party know that," said one GOP strategist. "So no matter what they're feeling, they're going to work for Miller as hard as they're working for gubernatorial candidate J. Marshall Coleman or attorney general candidate Wyatt B. Durette, because they're all in it together.