Republican John Warner's refusal to speak at a weekend convention of the Virginia state conference of the NAACP, the largest black organization in the state, drew an angry charge from the group's leader yesterday.

"We consider it an insult to the black people in the state," said Jack W. Gravely, executive secretary of the 23,000-member organization. "Republicans are still writing us (blacks) off."

Gravely said Democrat Andrew P. Miller, Warner's opponent in the U.S. Senate race, will speak to the group today at the Sheraton Motor Hotel in Arlington.

Richard Lobb, a Warner campaign aide, said Warner was unable to fit the NAACP meeting into his schedule. "This is no degradation to the NAACP," Lobb said. "John Warner has campaigned to black people. He hopes very much that black people will support him."

Warner's schedule for today calls for him to be at an oyster festival in Urbanna, a William and Mary football game in Williamsburg and a Republican dinner in Southwest Virginia.

Blacks, who represent an estimated 14 percent of the state's registered voters, are considered an important voting bloc in statewide elections and perhaps crucial for a Democratic nominee.

Efforts by Miller to win the backing of blacks have had only partial success, and some at yesterday's convention session voiced frustrated with his moderate-conservative campaign stance.

"I'm tired of voting for the lesser of two evils," said James E. Ghee, a lawyer and president of the Farmville chapter of the NAACP.

In Richmond yesterday, Miller received the endorsement of 250 black ministers, and representatives of the group said the pastors would speak out tomorrow on Miller's behalf from their pulpits.

But the Richmond Afro-American, a weekly circulated primarily among blacks, refused to endorse either candidate.

In an editorial, the newspaper said people or justice, and they have to proclivities for being such," the paper said.

"They are not the friends of black neither Warner nor Miller is fit for the Senate. It labeled both "fanatical worshipers of U.S. Sen. Harry F. Byrd Jr., an unyielding opponents of important measures."

Although the predominantly black Crusade for Voters endorsed Miller on Aug. 26, several political leaders expressed lukewarm feelings toward him last month at the crusade's annual dinner.

Even after a Miller breakfast with black businessmen last month at which Richmond Mayor Henry Marsh III said he saw no lack of enthusiasm for the Senate race, other leaders said privately afterward they were worried about voter apathy among blacks.

At a Hampton campaign appearance last month billed as a lunch with black ministers, only a few blacks showed up, leading one to say, "To tell the truth, it is a problem."

Part of Miller's problem among blacks, especially in the Tidewater area, appears to be his failure to give former Lt. Gov. Henry E. Howell, the populist who lost the gubernatorial race last year, a prominent campaign role.

"The ghost of Henry Howell will never die," said Junius Green of the Hampton Democratic Committee.

State Del. Robert Scott (D-Newport News) yesterday said he expects a low voter turnout among blacks.

But no matter how low, Larry Sabatio, a Univeristy of Virginia political scientist, said the black vote "is decisive." He said blacks generally compose nine or 10 percent of the total turnout.

Gravely said he hoped both Warner and Miller would speak to the NAACP, a nonpartisan organization that does not endorse political candidates.

Gravely said yesterday that convention delegates had hoped to question Warner about his controversial statement, made during a television interview, that he slowed efforts to integrate the Navy. Warner, a former Navy secretary, later amended the statement, saying he hadn't understood the question.

Gravely released yesterday a letter to Warner dated Sept. 26, in which he said, "Our theory is that you made the statement intentionally to signal the hard core conservative elements that you are still one of the 'good ol boys."