Virginia Republican U.S. Senate candidate Paul S. Trible, buffeted by internal dissension within his campaign and a series of tactical blunders, appears to have squandered a huge organizational and fund-raising lead in his race against Democrat Richard J. Davis, according to a number of Republican supporters and independent political experts.

The errors, focused primarily around Trible's handling over the summer of a controversial fund-raising memo, threw the Newport News congressman's once smoothly functioning campaign off track and has left him scrambling to regain the offensive ever since.

Last week, Trible was forced to unveil a new campaign them -- dubbed "Virginia First" -- after his chief strategist acknowledged that the old game plan of stressing national issues, such as the economy and national defense, had failed to lure Lt. Gov. Davis into debate.

"He's been on the defensive far more than he should be," says Roy Smith, the former Democratic legislator who is cochairman of the "Virginians for Trible" Committee.

"The political elites--the party activists, the campaign contributors--are getting the impression that Trible is off-balance, that his momentum has stopped," adds Larry Sabato, a veteran analyst of statewide races and a professor at the University of Virginia.

Trible's problems have also been a continuing disappointment to national Republican party strategists in Washington, who have counted on the Virginia race as the party's best nationwide shot for a GOP pickup this fall, according to several party sources. While party officials and Trible consultants publicly maintain a bullish confidence--they have recently touted a campaign poll showing him slightly ahead--many of the candidate's closest supporters have been privately urging him to adopt a far tougher and more aggressive posture towards his Democratic opponent.

For example, at a recent closed-door meeting of the coalitionists -- a shifting group of independent conservatives closely associated with the retiring Sen. Harry F. Byrd, Jr. -- Trible was urged to exploit Davis' reputed liberal past by linking him with State Sen. L. Douglas Wilder (D-Richmond), the state's ranking black official. Smith repeated this suggestion publicly last week.

So far, however, Trible has rejected this course, fearing that it could backfire by injecting sensitive racial issues into the campaign and alienate black voters. Yet moderate Republicans are convinced that the tack Trible has used to date of tagging Davis as a Teddy Kennedy Democrat has failed to stir the rank and file.

"I'm distressed by it," said Del. Clinton Miller (R-Shenandoah). "There's simply not the groundswell of enthusiasm out there that we need in order to win. Paul Trible has got to get away from running against Davis as though he were [former lieutenant governor] Henry Howell."

In part, Trible's dilemma has stemmed from a Davis strategy that even Republicans acknowledge has been masterful. Davis, 61, has virtually avoided any substantive discussion of issues, offering bland policy statements bemoaning high interest rates and unemployment and stressing his belief in a "strong national defense."

Even in the one case where Davis had gotten specific--advocating a deferral in the third year of the Reagan administration's tax cut--he subsequently appeared to water down his stance after Trible attacked it. Meanwhile, Davis' campaign has gleefully waged guerrilla warfare, frustrating the 35-year-old Trible with a barrage of minor attacks.

Just last week, while Trible was attempting to attack Davis for his failures to stand up for Virginia interests when the Carter administration sent the aircraft carrier Saratoga to Philadelphia, Davis was winning the newspaper headlines. The reason: a Davis charge that Trible had compiled the worst attendance record in the Virginia congressional delegation, missing key votes in the House. If nothing else, the publicity appeared to have kept Trible off the campaign trail and on Capitol Hill for most of Thursday when he showed up for all votes.

"I've got to hand it to him," said Ed De Bolt, latest in a string of political consultants to join the Trible campaign. "Dick Davis has effectively sidetracked the debate. He's a darn smart guy."

The concerns are most pronounced because of the overwhelming advantages with which Trible, a former Alexandria prosecutor, began his campaign. When the two candidates were nominated at party conventions in June, Trible had been campaigning for over a year and had a statewide organization in place. Davis, a white-haired millionaire mortgage banker from Portsmouth, was starting from scratch. By the time the first post-convention campaign finance reports came out in mid-July, Trible had compiled an overwhelming 16 to 1 fund-raising lead, outstripping Davis $520,983 to $32,465.

Yet the tensions within the Trible camp were long festering. At the outset, they centered on a fierce internal struggle between Trible's original New Right-oriented consulting firm, Black, Manafort and Stone, and his campaign manager Judy Peachee. There were also mishaps. At one point, the consulting firm sent out a statewide fund-raising appeal that mistakenly included 5,000 pieces of literature for L.A. (Skip) Bafalis, a Florida gubernatorial candidate.

In June, Trible sided with Peachee, fired Black, Manafort and hired a new consultant Robert Weed, who managed his first campaign for Congress in 1976. His problems with the New Right have yet to dissipate. Two weeks ago, Trible told an Arlington candidate's forum that he opposed a constitutional amendment banning abortion. Hard-core conservatives, who felt they had a commitment from Trible to support an amendment, were infuriated.

"There are a lot of party workers out there who feel strongly about this issue and they're just going to sit on their hands," grouses Ray LeJeunesse, a Republican Central Committee member from Arlington.

By far, the most serious blunder in the campaign was Trible's response to Davis' charges over the fund-raising memo. The Aug. 11 memo, written by Peachee and mailed to GOP supporters, purported to describe a New York meeting of the AFL-CIO's Committee on Political Education (COPE) at which Davis staffers previewed TV spots and solicited campaign contributions. After obtaining a copy of the memo, the Davis camp insisted no such meeting ever took place and called it "a malicious falsehood."

For more than three weeks, Trible ducked questions about the memo while Davis attacked his "lack of integrity" on the matter. Finally, the day after Labor Day, Trible called a Richmond news conference at which he virtually pleaded with reporters to turn to other issues. "Doesn't anyone here care about a balanced budget?" asked the candidate at one point.

Although few contend the memo itself carried much weight with the voters, Trible's handling of the matter mired him in a quagmire from which he has yet to fully emerge. "It was a little like Watergate," said state Sen. Ray Garland, R-Roanoke. "Once you start stonewalling, how do you bail out?"

"That memo could have been put to rest in 48 hours if there had been a meeting of the minds," says Smith. "It threw the campaign off to the extent that he had to go on the defensive and that's always bad."

Most significantly, according to Sabato, the memo deflected Trible from pressing his advantage at a time when Davis was still getting his campaign off the ground. "He could have been challenging Davis on the issues on a daily basis," he said. "He could have been positioning his opponent as 'the invisible candidate.' "

Neither camp pretends the opportunity lost cannot be recaptured, particularly because of a still sizeable money lead that should give Trible a distinct edge for a late-October media blitz. (Trible expects a final war chest of about $2.2 million; Davis, who has now raised about $600,000, expects to spend about $1.2 million.)

Yet Trible's recent poll showing him several points ahead, conducted by official campaign pollster Lance Tarrance, is now considered of dubious value. It was conducted between Aug. 10 and 12, before most of the problems beset his campaign. Last weekend, new consultant De Bolt began his own polling to assess the damage.

"They've had a rough couple of weeks," said consultant De Bolt of the Trible campaign. "But my polling shows that if Paul Trible can talk about the issues, he's going to win."