Virginia opponents of slain civil rights leader the Rev. Dr. Martin Luther King Jr., including segregationist groups, have launched a major letter writing campaign aimed at pressuring Gov. John N. Dalton to veto a bill designating King's birthday a state holiday.

Dalton said this week that he has received almost 3,000 letters about the bill which was passed by the General Assembly this session after some deft maneuvering by the state senate's only black member, L. Douglas Wilder of Richmond.

"That's more mail than I can remember having gotten on any issue since I've been governor, " said Dalton, who would not reveal whether he will sign or veto the bill which would make King's Jan. 15 birthday a state holiday. The overwhelming majority of letters, according to the governor's office oppose the holiday.

Besides the letters and phone calls from segregationist groups, Dalton has been lobbied by some the same conservative business interests which financed his 1977 gubernatorial compaign.

"Martin Luther King's not anbody's hero except those who are trying to make trouble," said Clifford Miller, a Richmond building materials manufacturer and a major GOP campaign contributor in recent years. Miller said he has already written two letters to Dalton. "It'd be shameful for the state to honor him. Doug Wilder made a mockery out of the General Assembly."

Wilder said he is not surprised that the bill is being fought by groups traditionally opposed to honoring King -- groups he describes as "the sons and daughters of whatever." But Wilder, a Democrat, said support of the bill has also been registered with Dalton, including a petition with 500 signatures from "mostly white" University of Virginia students.

"I hope this won't be determined by who has the best letter-writing campaign," said Wilder.

Jack Gravely, Virginia's NAACP director, said this week that he believes the governor has already made up his mind to veto the King bill, even if Dalton's office claims a decision won't be made until Monday, the deadline for vetoing legislation passed this year.

"I never expected the governor to sign that bill, so it will not be a big surprise to me when he doesn't," said Gravely, who warned that Virginia's black community would regard the veto as an insult.

"The Martin Luther King birthday bill is only a symbol," Gravely said today. "But if it is an indication of what the Republican Party is going to do in this political year. . . then I think it is tantamount to spitting in the wind."

A veto could rebound to hurt J. Marshall Coleman, a Republican seeking to succeed Dalton, Gravely said. Coleman, Virginia's attorney general, has indicated he will attempt to win the state's traditionally Democratic black vote from Lt. Gov. Charles S. Robb, the Democratic party's nominee.

Charles Davis, a Dalton aide, said today the predominant sentiment of letters and calls opposing the King bill was that the civil rights leader was not a native Virginian, "They point out that there are other black Virginians who should be so honored if there is to be a day of recognition," said Davis, mentioning Booker T. Washington and George Washington Carver as likely substitutes for King.

Former Virginia Governor Mills E. Godwin, who vetoed a King Holiday bill in 1977, would not comment today on a report that he had called Dalton, his successor and fellow Republican, to offer advice. But Godwin did say what he would do if faced again by the King measure.

"If I were governor, I would not sign the current bill, " said Godwin.

The president-general of the United Daughters of the Confederacy, Trippett Boineau, said from the group's headquarters in Richmond that the organization itself is not supposed to participate in politics. "But I'm certain," said Boineau, "that you have a lot of individuals [from the organization] who are taking part in this."

Whether the state should honor King has been a subject of debate among Virginia lawmakers for years. Three years ago Wilder succeeded in persuading the General Assembly to approve Jan. 1 as a day to honor King. But Wilder let it be known then, that a day historically given to nursing hangovers, was not suitable for King.

"I figured that if I could get the camel's head in the tent first, the rest of the camel would go in easier," said Wilder when he introduced his King bill this year.

By a surprising 30-to-8 vote, the state Senate voted to move the King observance from New Year's Day to the third Monday in January -- a state holiday currently honoring two Confederate generals, Robert E. Lee and Stonewall Jackson.

News of the move created a storm of opposition in this former capital of the Confederacy. But on the day of a House hearing on the King bill, Wilder changed gears and made a tactical surrender of Lee-Jackson day, deflating the prepared arguments of those who had packed the hearing room to rail against upstaging the Confederacy's biggest holiday.

Instead of the third Monday in January, Wilder suggested that the King holiday be moved to Jan. 15, King's birthday and the date Wilder wanted from the beginning.

Wilder would not speculate today on what Dalton will do with his bill, but he did offer a warning of his own. "If he vetoes this bill, the governor will be marrying history in a way that will be fixed in cement," said Wilder.