In bold red and black letters, the full page ad in The Winchester Evening Star blared the message: "Andy Miller Tells the Truth . . . John Warner Fudges . . . Vote Honesty . . . Vote Miller."

It was a shocking frontal assault on Republican senate candidate Warner in a citadel of Virginia conservatism and it hit the streets of Winchester on the day that Warner stood in the courthouse square there to plead for the opportunity to take the "Virginia philosophy" to Washington.

For 10 years, Virginia Republicans have taken advantage of a Democratic flirtation with leberalism and populism to strip the Democrats of the almost unchallenged political power they held over the state for 80 years.

State GOP leaders are determined this year to close their grip on the allegiance of the conservative electorate by painting Democratic nominee Andrew P. Miller, a moderate-conservative former attorney general, as a willing supporter of the vanquished liberal candidates of the past decade.

As the U.S. Senate campaign ends this weekend, the Republicans find themselves apprehensive that a series of misstatements by political novice Warner has made him the issue instead of loyalty to Virginia's conservative faith.

Despite the Warner adversities, polls by the Richmond Times-Dispatch and both campaigns indicated by the end of October that the Republican had cut deeply into an early Miller lead and was running almost even by the last week of the campaign.

After two months of campaigning, the GOP nomines was thoroughly enmeshed in apparently contradictory statements about his civil rights policies as secretary of the Navy, his past political contributions, his attitude toward organized labor and the influence of political connections and his former ties by marriage to the wealthy Mellon family on his appointment to the cabinet of former president Richard M. Nixon.

Moreover, public attention remained focused on his second wife, actress Elizabeth Taylor. Polls showed that voters were closely divided over whether she would help or hurt his election chances.

There was never any question about her ability to dominate headlines. When she swallowed a chicken bone at a banquet in Big Stone Gap and was hospitalized for a week, neither Warner nor Miller could compete with her for public attention.

Miller capitalized on Warner's loans of $812,000 to his convention and general election campaigns, by charging that Warner, a millionaire, was attempting to win the right to replace retiring Republican Sen. William L. Scott "on the depth of his (Warner's) pocket."

By the end of October, the struggle for the allegiance of VIrginia's conservative electorate had become an epic obscured by subplots generated by the Warner candidacy.

Miller seized on the Warner misstatements to assert that the "issue in this campaign is credibility." Such Warner supporters as Republican Rep. M. Caldwell Butler tried to dismiss the Miller attacks as "political nitpicking," but other GOP leaders were dismayed. "Andy has not had a single issue that Warner has not handed to him," said one anguised GOP strategist.

In June, the Republicans had been confident that their original nominee, former party chairman Richard D. Obenshain, would set up another classic test of conservative purity and produce another GOP victory in the only state in the nation that has failed to elect a Democratic governor or senator in the past 10 years.

Obenshain was working with former Gov. Mills E. Godwin to revive once again the coalition of conservative Democrats and Republicans that had sustained GOP successes in that decade. Godwin was the last governor produced by the old Democratic Byrd organization and was elected to an unprecedented second term as a Republican in 1973 in the midst of Democratic Party strife.

But in August, Obenshain was killed in a plane crash and Warner was nominated by the party's central committee to replace him. Godwin stuck by Warner, but it soon became clear that the change of candidates and the Warner missteps were eroding conservative support.

At a breakfast gathering of old Byrd organization Democrats in Richmond on Friday, longtime Godwin allies attacked both him and Warner in an astonishing series of speeches.

Former governor Colgate W. Darden, 81 compared conservative Democrats like Godwin who left the party unfavorably with those who stayed in. "I'm not an apologist" for remaining a Democrat, he said, "because these people running around afraid of being said to be a Democrat when they've lived in the party for years and years don't appeal to me."

It was clear at the breakfast that the conservative Democrats' scorn for Warner would not have been directed at Obenshain. "Obenshain was a fine fellow," said former congressman Watkins M. Abbitt, a speaker and former Democratic party chairman.

Abbitt contended that "all the conservatives to a man were agin'" Warner when Obsenshain narrowly defeated him at the state GOP convention, but adopted him as their only choice after Obenshain's death.

"The hierarchy in that party stirred around and looked to others," he said, "but when it developed they didn't have but one choice they brought him down here . . . they took the into the inner sanctum and after about three hours they brought him out, having wrapped around him the robe of their dear, dead brother. But it still was the voice of John Warner."

While Miller apparently has succeeded in recapturing important conservative support for a Democratic candidate, his party's leaders are worried about his failure to attract enthusiastic backing from the traditional Democratic voter blocs - blacks, labor and liberals.

Miller upset followers of his intraparty foe, populist former lieutenant governor Henry E. Howell, by excluding Howell from any formal role in his campaign. He also has shunned help from President Jimmy Carter while bringing in a parade of conservative Democratic senators to campaign with him.

The coolness for Miller among blacks and labor is compounded by the double-jointed dexterity he displays when he takes positions on issues important to them.

For instance, he said he would vote to deny food stamps to strikers but not to their families. He also said he would vote against extension of the Voting Rights Act when it expires, but only if Congress refuses to apply it to all 50 states.

Black Virginians regard the act as an important safeguard of voting rights systematically denied to them during the years of conservative Democratic rule.