Jeanne Blackistone Mandel was calm and collected yesterday at Prince George's General Hospital. Her husband, the governor of Maryland, was resting peacefully on the ninth floor. She has just delivered to him the latest on the sales tax vote, scheduled for later in the day.

"This is no time to Mickey Mouse around," she said she had told Mandel's staff at the governor's direction. "Get out and get the job done," she had said.

The measure looked safe yesterday afternoon. She had done her job and she felt good about it. "Let there be no doubt in anyone's mind that Marvin Mandel is still running the state of Maryland," she declared self-assuredly.

At this time of crisis, she was in her full glory - the dutiful wife, who thinks of herself as a shrewd political operator, scurrying between Annapolis and the hospital in Cleverly, protecting her husband's interest, and holding the state government together.

She had spent most of the previously day relaying messages between the State House and her husband's hospital room, doing what she could to direct the sales tax vote, Mrs. Mandel said. "As I said yesterday, I'm trying to be the governor's eyes and ears, arms and legs."

Messages were delivered to the governor's staff from the telephone in the hallway outside the governor's room.

A remark by Gov. Blair Lee III Wednesday disturbed her. He had said he and several key members of the governor's staff had drafted memos for the governor that day, and "Mrs. Mandel graciously consented to be a courier."

She had sat in the governor's overstuffed chair in his State House office when the memos were discussed, and she obviously felt her role understated. But she had nothing but praise for Lee, whom she described as "a true gentleman," and the governor's staff.

"My whole purpose has been to pacify the governor while he is recovering and keep him in touch with what's going on," she said. "In my little way, I'm helping out in every way I can. If being called a gracious courier is helpful, I'll accept that."

"Jeanne Mandel doesn't want any credit, Jeanne Mandel only wants to see that a job gets done," she added later.

There was little word on the governor's condition yesterday, no further confirmation that he had suffered a "milk stroke" as his doctor, Perry Hookman, said Wednesday.

Mrs. Mandel said her husband had undergone two series of tests during the last 24 hours. His sleep had been interrupted by a fire in the 635-bed hospital at 4:30 a.m., and he was still experiencing severe headaches, she said.

Mandel was hospitalized Tuesday, eight days before his second trial for political corruption was scheduled to begin. The case, pending against Mandel and five codefendants since indictments were issued in November, 1975 has been marked by a bizarre series of delays and occurrences, including a mistrial declared last December after two jury-tampering incidents.

His hospitalization also occurred during the crucial final days of the state legislature, a time when several of Mandel's key programs were still awaiting action.

This, Mrs. Mandel said, put the pressure on the governor's staff and Lt. Gov. Lee as never before. "Sometimes I think no one appreciates how much Marvin has done," she added. "He's given up nine years of his life to the state of Maryland, and where does he end up - in a hospital room in Prince George's County. And he's still up there fighting for people of Maryland.'

She has often felt this way in the previous crises Mandel has weathered almost constantly since he left his first wife of 32 years of marry Jeanne, she said. "I know there's been times when I've picked up the newspaper and asked him, 'Is it worth it,' and he says, 'everything that I give to the state of Maryland is worth.'"

If he doesn't recover fully, would he consider resignation? "Asolutely not," Mrs. Mandel declared. "I know Marvin Mandel too well. At this point, I know he'll be governor until his term is up."

Meanwhile, Mandel's exact condition and the impact of his hospitalization on his political corruption trial, scheduled to begin next Wednesday, was unclear. On Wednesday, the governor's family physician, Dr. Hookman, said he may have suffered a "mild stroke" that would make it unwise for him to stand trial.

Hookman couldn't be reached for further comment yesterday, and a neurological consultant brought in on the case was considerably more cautious in his diagnosis.

"I don't have the whole picture yet - I will e reviewing all the findings at the hospital tomorrow morning - but there's no question in my mind but there is a physical basis for Gov. Mandel's complaints," said Dr. Marvin Korengold, the consultant.

"My own estimate at this point is that there is an organic, a physical problem. It is real, it is not psychosomatic," though such a physical problem could have been caused by emotional stress, he added.

Korengold Wednesday night completed a "CAT scan": a complete x-ray picture of Mandel's head, brain and attendant blood vessels, made by using a computer to add up multiple views taken from many angles. But he said he had to add his information from this source to information from other tests to make a diagnosis.

He said he was highly hopeful that the problem, thought physical, may be a temporary one or one that does not leave serious permanent effects. "But that is my estimate at this point, and I have to see more," Korengold added.

Mandel's chief lawyer, Arnold M. Weirer was "out of the office" and not available to comment on whether he is drawing up motions seeking to postpone the trial.

It was believed that the Mandel defense team would await further medical information before iniating any legal action, although some call for a delay appeared inevitable.

If Mandel's lawyers succeed in getting a delay, the next question is what will happen to the five other codefendants.

One defense attorney indicated that if Mandel were granted a delay, all of the co-defendants would happily accept the same delay.

"A defense attorney would be happy if he never goes to trial," he said. "Time tends to be on the side of the defendants."

One lawyer suggested that "the closer Mandel gets to being a lameduck governor (his term experies the end of next year) the more likely some of the prosecution witnesses are ot mellow in their testimony."