Four Prince George's County interest groups, including the NAACP and the local police union, plan to call today for the rejection of police chief nominee James R. Taylor, sources said last night. The move could be a critical blow to Taylor's chances for confirmation by the County Council.

Leaders of the local NAACP, Fraternal Order of Police, the county's chapter of the National Conference of Christians and Jews and the Prince George's County Concerned Clergy agreed last night to hold a joint press conference in Upper Marlboro today to oppose Taylor, the sources said.

However, the NAACP's position opposing Taylor was dependent on approval of its executive board, which was being consulted by phone early today. Sources said NAACP board members were being heavily lobbied by both Taylor's supporters and opponents, and last-minute reversal of the group's position was considered possible.

The County Council will consider Taylor's nomination next Monday. Several council members who have remained neutral on the appointment have said in the past week that the position of black groups -- particularly the NAACP -- on Taylor could decide the council's vote.

"If it's a strong rejection, it would make it extremely difficult for the man to be approved," said council member Francis B. Francois last night. Taylor must receive at least four of the 11 council votes to be confirmed.

Taylor, nominated for the Prince George's job two weeks ago by County Executive Lawrence J. Hogan, is chief of the Petersburg, Va., police force.

Taylor's success in winning over county black leaders has become a crucial issue for the council because Hogan has stressed the importance of appointing a new chief who can improve the police department's image with the black community.

Hogan said, in nominating Taylor, that his candidate had a particularly outstanding record of working in two cities with majority black populations. Since then, however, that record has been challenged by black leaders in the cities, Petersburg and Newburgh, N.Y.

In Prince George's, Taylor was endorsed by several county black leaders last weekend and Hogan's top aide on police issues predicted last night that today's statement would not carry decisive weight.

"I'm not surprised," said Jack McHale, who led Hogan's five-month search for a chief following the retirement of John Rhoads on a disability pension last June. "I don't know how the council will perceive it. Obviously the black groups have split. Actually, I think there are still more black leaders for him than against him.'

Reached at his home last night, Taylor refused to comment.

The Fraternal Order of Police and the NAACP have conducted investigations of Taylor's record and are expected to announce their findings at the press conference.

Several council members said last night that they would be influenced by the groups' call for Taylor's rejection only if the groups investigative findings back up their position.

"It's going to be tough to vote for him now," one council member said. "But I've got to see what their reasons are."

The joint press conference will represent the formation of an unusual alliance on a police issue between the Fraternal Order of Police and black leaders.

Only six months ago, the police union and the black leaders were sharply divided by the case of Terrence Johnson, the 16-year-old black Bladensburg youth who was on trial in the shootings of two white police officers. The president of the police union, Laney Hester, and the leader of the County Concerned Clergy, Perry Smith, appeared on a television debate and sharply attacked each other.

However, Hester's union split just as bitterly last week with Hogan's administration on the police chief issue.

At a press conference, Hester accused Hogan of trying to force him into supporting Taylor's confirmation, and bitterly referred to the executive as the "Ayatollah Hogan."

Hogan, in turn, called Hester an "Alabama racist" and charged that Hester would oppose Taylor because Hogan had rejected a political deal on the police union's current contract negotiations.

It was the split between Hogan and the police union, and the union's concerns about Taylor's qualifications for chief, that led the union leaders to join with the NAACP, sources said.