BALTIMORE, OCT. 21 -- A federal judge declared a mistrial in the opening hours of the racially tinged conspiracy trial of Maryland politicians Clarence and Michael Mitchell today after a prospective juror reportedly told fellow jurors he hoped to serve on the case so he could "shoot" or "kill" the Mitchells.

The courtroom, filled with about 100 prospective jurors and numerous court officials, reporters and members of the public, was thrown into momentary confusion when Judge Norman P. Ramsey declared the mistrial and ordered a new jury pool convened on Thursday.

Prospective juror Glenda Hall of Baltimore told reporters later she told Ramsey that she overheard another prospective juror in the jury assembly room say to several other persons, "I hope to get on the Mitchell case because I'd like to shoot both of them."

At another point, Hall told reporters the prospective juror may have said "kill," rather than "shoot."

Trial attorneys who attended the bench conference with Hall and Judge Ramsey confirmed her general account. They said they did not believe the man literally meant he wanted to "shoot" or "kill" the Mitchells, but was expressing a desire to see them convicted.

The account, like the trial itself, took on racial overtones. Hall, who is black, described the prospective juror as an "older white man." When he made his remark, Hall said she replied, "I see you guys have gone beyond sheets and crosses . . . {and} are just killing them now."

Clarence M. Mitchell III, a former Maryland state senator, and his brother Michael B. Mitchell, a former Baltimore City Council member and now a state senator, are black.

The white prospective juror was not identified.

Attorney Abbe D. Lowell, along with other defense attorneys, asked for a mistrial, contending that the remark of the white juror, audible to others in the jury assembly room, could taint the jury ultimately selected for the Mitchell trial.

Ramsey agreed. Grim-faced and speaking through clenched teeth, he dismissed all 100 prospective jurors, saying "We do not let jurors who make prejudgments sit on our juries."

He ordered court clerks to convene another panel of prospective jurors on Thursday and start the jury selection process over again.

The Mitchell brothers, usually outgoing and willing to talk to reporters, made no comment as they left the courthouse today.

The Mitchells are charged with accepting $110,000 in payoffs to try to block a congressional investigation into the Wedtech Corp. of New York in 1984 and 1985.

The House Small Business Committee, then chaired by the Mitchells' uncle, former U.S. representative Parren J. Mitchell (D-Md.) was looking into whether Wedtech, a minority defense contractor, received preferential treatment because of intervention by White House officials, including Edwin Meese III, counselor to the president at the time and now attorney general.

According to a 14-page indictment, Wedtech officials wrote checks totaling $110,000 to the Mitchell family law firm to block the investigation. Michael Mitchell, a member of the firm, gave $25,000 of the total to Clarence Mitchell, who is not in the law firm, according to the indictment, and an additional $33,332 to Wedtech consultant Anthony Loscalzo as a kickback for steering Wedtech's business to the Mitchells.

The Mitchells have denied the charges, contending the payments were for legitimate legal services. Prosecutors have said Parren Mitchell was not involved in the alleged scheme.

The Mitchell brothers contend that the prosecution against them is designed to deflect attention from Meese, who himself is under investigation by independent counsel James C. McKay for his alleged role in providing White House favors to Wedtech.

They also maintain there is a Reagan administration vendetta against blacks active in civil rights.