Maryland Gov. Marvin Mandel's display of physical uncertainty, strain and fatigue overshadowed important procedural decisions today during the first day of Mandel's retrial on political corruption charges.

Mandel appeared groggy and weak as they day wore on, after closing his eyes, rubbing his forehead and complaining of headache. As he entered the building, he stumbled to his knees on the courthouse steps as reporters closed in around him.

"Get away, get away. Oh my God, he's falling down," shouted his wife, Jeanne Mandel. The governor later said he had been pushed and tripped over some wires.

When Mandel and his five codefendants reached the courtroom, presiding U.S. District Judge Robert L. Taylor swiftly denied a motion by several defense lawyers that would have allowed members of the trial jury to go home at the end of each day instead of being confined to a hotel.

The first trial ended Dec. 7 after 2 1/2 months of testimony when jurors, who had not been sequestered most of the trial, were exposed to jury tampering efforts and news reports about those efforts. Judge Taylor did not even hear arguments on the defense motion, but instead quickly began the lengthy process of selecting a 12-person jury for this trial.

Mandel is charged with accepting bribes in the form of expensive gifts and vacations from the codefendants - W. Dale Hess, Harry W. Rodgers III and his brother William A. Rodgers, Ernest N. Cory Jr. and Irvin Kovens - in exchange for using his office to help their business interests, including Marlboro Race Track in Prince George's County.

The retrial had been postponed following Mandel's hospitalization April 5. A team of physicians never firmly diagnosed what was causing his headaches and mild physical impairment on his left side although they said it may have been a small stroke.

A brief interview with reporters Tuesday and today's appearance at the courthouse were the first occasions anyone outside an intimate circle of family and advisers had actually seen the governor for any length of time.

Mandel stepped from his state car at 10:40 this morning and was immediately besieged by a throng of reporters, photographers and television crews. As he crossed into the building, the crush became impenetrable and the governor tripped as he was climbing three low steps leading to the doorway.

He fell to his knees on the step but was quickly rescued by his bodyguards. Mrs. Mandel began shouting and pushing reporters out of the way and the group finally made its way into the courthouse.

"I was pushed and tripped over some wires," Mandel said of the mishap. His wife said it took Mandel an hour to recover from the accident that sent him to his knees.

Mandel appeared confused and tired immediately after the incident and his attorney, Arnold M. Weiner, said that tears appeared in the governor's eyes afterward.

For Mandel, who has said he cannot concentrate for more than 90 minutes at a time before becoming fatigued, it was a long day.

By the time jury selection recessed at 4:55 p.m., he said he was "very tired . . . Court lasted longer than I thought it would. When I get tired, it (his head) starts to hurt," he said. "That's part of the problem."

Last Friday doctors declared Mandel sufficiently recovered to stand trial on a limited, four-day-a-week schedule. Judge Taylor delayed a ruling on whether to depart from the normal five-day schedule until after a jury is selected.

Mandel said he will delay his decision on whether to appoint Lt. Gov. Blair Lee III "acting governor" until the judge decides on a regular court schedule.

He said he anticipates "no problem" in working out with Lee how much authority the lieutenant governor would be given, including the question of who makes appointments.

Lee said today that on Monday Mandel approached him for the first time to discuss the problems and mechanics of turning over the workings of government on a temporary basis. According to Lee the governor expressed concern about the handling of his appointment power: who would actually make the nominations for the judgeships, commissionerships and other posts to be filled in the coming month? Would Lee or Mandel have the final say?

"I suspect that in the back of his mind he's got appointments he wants to make sure are made," Lee said, adding that he told Mandel that those appointments could be made as Mandel saw fit, with Lee stipulating at the time of appointment that he was following Mandel's wishes.

"I said I would not like to look like a puppet and he said he would not want me to look like a puppet . . . I would need to consult with him from time to time but he would not expect me to run over there two times a day to clear everything," Lee said. "I wouldn't operate that way."

The goal of today's preliminary questioning oppotential jurors is to select a pool of 42 persons from which the final panel will be chosen. Ten of the first group of 40 jurors were excused before today's session ended. Among them was the mother of several small children who said she could not tolerate the drive from her Salisbury home to Baltimore. A man was let go when he said he had planned to attend his sister's wedding in Texas. The judge sent him off as a wedding gift and with "the blessing of all these lawyers."