Former senior assistant postmaster general James V. Jellison said yesterday that he was demoted and former postmaster general Paul N. Carlin was fired because they both resisted efforts by members of the U.S. Postal Service's board of governors to award a contract to a Texas firm without competitive bidding.

Two weeks after Albert V. Casey succeeded Carlin as postmaster general, Jellison said, he was told he was being demoted by Casey because of poor relations with the board of governors and with the deputy postmaster general. Rather than accept the demotion, Jellison quit.

A spokesman for the board denied Jellison's charge. "No governor had any influence at all on Casey's decision," said David Harris, secretary to the board. " Casey canned him. The board didn't can him." Casey's office said he had no comment.

The board of governors has repeatedly denied that it fired Carlin because of his resistance to contract proposals. Members cited Carlin's indecisiveness and unresponsiveness as reasons for their decision.

Jellison's remarks, made in an interview, came as the House Post Office and Civil Service Committee concluded a hearing this week into the board's conduct. When asked during that hearing whether the board of governors was involved in the firings or demotions of a list of postal officials, board chairman John R. McKean denied that he was personally involved in any of the cases and singled out Jellison as a hard-working career executive who the Postal Service should not have lost.

But McKean declined to say whether other board members were involved. Congressional sources said former board vice chairman Peter E. Voss frequently attempted to influence personnel decisions.

The hearings were the latest in a series of investigations prompted by Voss' admission last month to charges of embezzlement and accepting kickbacks in a scheme to steer an equipment contract to Recognition Equipment Inc. (REI). The company denies knowledge of the kickback scheme. Several investigations are continuing into allegations of impropriety in the postal service.

Jellison said Voss was trying to push him and Carlin into accepting a sole-source contract with REI, which Jellison called improper and inefficient. "We knew his position and board governor Ruth Peters' position was totally irrational. We didn't know if it was stupidity or whether there was something more involved, but we all thought it was just crazy," Jellison said.

In an affidavit made public at Wednesday's hearing, Carlin said on July 8, 1985, the board of governors considered a proposal that would have guaranteed a contract with REI. Two days later, Carlin said, the attorney who wrote the proposal, Gerald M. Rosberg, paid an evening visit to Carlin's house and told him that a decision to contract with REI "could send someone to jail." According to Carlin, Rosberg told him that "I was the only one who could stop it." Rosberg could not be reached for comment.

Six days later, Carlin sent a memo to the board of governors informing members that he was taking "a series of steps to ensure the absolute impartiality and fairness of the procurement process." Carlin called for a postal inspector to monitor procurement and "report immediately any sign of attempted interference." Ultimately, the postal inspectors notified the Justice Department of Voss' actions.

Board of governors secretary Harris said the board had the option of choosing between two competing firms.