at 3 p.m., it was Hamilton Jordan, on the phone with the entire Cabinet, standing beside his desk as he talked, wearing a pin-striped suit that will be his born-again accouterment and telling the Carter Cabinet members that the White House was going to announce they all had offered to resign.

at 3:15 p.m., it was Hamilton Jordan at the head of the table in the Roosevelt Room, telling the White House senior staff members that the Cabinet had just offered to resign and that perhaps they all should as well.

"today was the day that Hamilton Jordan took charge," said one of the president's closest advisers.

It was a day that began with the president making it all perfectly official, if not perfectly clear. He convened a Cabinet meeting, asking that Jordan be the only White House aide present, and then reportedly told his Cabinet: "Ham Jordan is the chief of staff."

It is the title Carter had long refused to confer, feeling that it carried with it all of the bad plumbing from the days when H. R. Haldeman made the trains run on time while he was making Richard Nixon what he is today. All senior aides would be equals at the Carter White House, this president believed. But gradually Carter had come to see he was presiding over disarray, and so for the past year Jordan has tried to function as a de facto chief.

Now he will have the official power to hire and fire. All other senior assistants will report to him and he will resolve in-staff disputes. "Somebody is going to be in charge here for a change," said one senior adviser.

"And that somebody is Hamilton Jordan."

It is a name that comes with cadence, like those in novels of the Deep South. And like those characters it is a name that has become a household word (and a Johnny Carson monologue fixture), largely because of stories that have been embellished with as much fiction as they ever had in fact.

Hamilton Jordan is the man Carter feels was most responsible for making him president - he once told this to a Democratic congressman in a monologue that grew out of a White House chat, as he went on a great length about the attributes, intuition and skills of Jordan. But the public has not come to know Jordan for this. It has come to know him through a lore that grew from a couple of reports of social incidents - reports that Jordan has denied. One involved the bodice of the wife of the Egyptian ambassador; another was a yarn about a barroom and a woman and amaretto and cream.

These gossipy bits were tickling America's prurient fancy at about the time that Jordan was making the networks and newspapers because of his fondness for coming to work at the White House in khakis and open-collared shirts, and making the cover of the Rolling Stone clowning with Jody Powell in derby and cane.

Now Jordan sports a wardrobe of business suits, and those close to him say the change goes far deeper than his clothes. "Hamilton is a changed man," says one senior adviser, who concedes that he is concerned that Jordan's public image is not as strong as his political abilities. "there as been a change in his approach to his job - and in his personal life. He understands what this new role will require."

Yesterday, what Jordan's new role required was that he orchestrate the resignation offers of the Carter cabinet and White House senior staff. He was, from the moment Carter menioned him in the Cabinet meeting, the most equal among the Carter equals.

The president discussed the matter of receiving offered resignations from his Cabinet at that meeting, and then they went around the table and everyone had a say. There is some question, however, about whether all Cabinet members left the White House with the clear understanding that they all had offered officially to resign, and that this would soon be made public.

But there was no misunderstanding after Jordan placed his conference call to the Cabinet. Every Cabinet officer was on the line except Treasury Secretary W. Michael Blumenthal (who said he was going to the White House anyway, so he didn't need to listen in, a Treasury source said).

Jordan said he was calling because the White House was going to put out a statement on the resignation offers. And he read it to them.

Then he hung up and walked a few steps along the corridor to the Roosevelt Room, where the senior staff had assembled at his order.

Jordan began this meeting by saying that the Cabinet had just offered to resign, and that some of the staff had suggested that they "ought to be in the same position as the Cabinet in this." It is a matter of freeing the president to exercise all his options as easily as possible, Jordan said. Those who were present say everyone agreed.

This done, the senior staff adjourned - in somewhat better spirits than the stunned bunch of White House aides who walked out of that same room the day after the 1972 election. Richard M. Nixon had dropped in that day to thank everyone for their efforts and when he left, Haldeman moved to the head of the table (where Jordan sat yesterday).

According to John Dean, writing in "Blind Ambition," Haldeman said: "The president has directed that everyone in this room also hand in a letter of resignation. . . We just want to show we mean business." And then he left the room to tell the Cabinet the same thing.

Yesterday, the Carter White House decided not to wait for anything so chancy as a reelection to make their changes.

Jordan comes easily to his role as chief of staff, because he has in many ways been functioning as chief since April 1978 - the last time Carter went to Camp David and came back resolved to whip the Cabinet and sub-cabinet into line, to be a leader and to make everything work.

At the time, Carter counted on Jordan to curb the independence of the Cabinet and to bring the subcabinet under White House discipline. Jordan began holding meetings at 3 p.m. every Wednesday for the senior staff and representatives from each Cabinet department.

"either Ham or (his aide) Tim Kraft would have a horror story each week," one source recalls. Once Jordan complained at a meeting that an Agriculture Department congressional liaison aide had drafted on a congressman some sugar legislation that was contrary to the White House positions. A department aide interrupted to say that Jordan just "didn't understand" that this was often done as a courtesy. According to one White House aide who was there, Jordan exploded.

"that just indicates the scope of the problem," he said, "that someone thinks he can sit here and tell the president's number one aide thathe does not understand." CAPTION: Picture, HAMILTON JORDAN . . . White House strong man