There was a time, a few months ago, when the man who wants to be president couldn't get a table in a crowded restaurant, a time when he'd pass through the nation's busiest airports without anybody recognizing his face.

Often he traveled with only one companion, an aide young enough to be his son. When a reporter would drop by for a day or two, the candidate was introspective. He would linger into the night over a vodka martini, baring the crevices of his soul. When he gave a speech, the candidate would spend half his time explaining who he was and how he could win. c

Those days are over for George Herbert Walker Bush. Now he travels with an entourage of more than 25 aboard his own campaign plane, a goose-like twin-propeller Fairchild dubbed Asterick One for the days when he was only an asterick in the polls.

The old intimacy is gone.

Three television networks record every move. Interviews are parcelled out sparingly. They have been replaced by crowded, noisy news conferences, where at every stop Bush is asked to give lofty pronouncements on the state of the world. And when he goes for his daily three mile jog, television cameras go with him.

But in may ways Bush is still campaigning as if he were a lonely, long-distance runner with on one looking over his shoulder.

He hasn't added a new joke or line to the standard stump speech he has been giving at least since October. He has been ill-prepared to respond to simple questions about basic issues as they arise.

When he was asked about President Carter's new budget this week, his replies were vague and sometimes contradictory. In Buffalo, he lambasted the budget. But by the time he got to the next stop, in Rockford, Ill,. he was saying, "Generally it's not a budget you can be excessively critical of."

Perhaps more telling was a lighthearted question asked Bush yesteray: did he or did he not favor an embargo of Stolichnaya vodka from the Soviet Union.

Bush acted as if he had been thrown the world's hottest potato. "I've got to be careful. I'd have to know where it's bottled and if it's bottled in the United States, how many people are employed doing it," the former CIA director stammered, before saying that, if all goods were embargoed, vodka should be included.

Bush's campaign organization has also had trouble adjusting to the new interest in the candidate since his upset victory over Ronald Reagan in Iowa precinct caucuses last week.

When the press contingent traveling with Bush swelled after the caucus vote, his staff failed to build time into the schedule for reporters to file their stories. That was a week ago.

This week, ample filing time was put in the schedule, but one half of the originally scheduled events the press had hoped to cover were either canceled or closed.

So reporters ahd plenty of time to file, but little to write about. And when Bush left here today to campaign in Florida and Arkansas, Asterisk One was sent to Texas for repairs, leaving the candidate with no way to take his newly mushroomed traveling press corps along.

The troubles were more an embarrassing annoyance than a major problem, as Bush made a two-day campaign swing through Illinois, the site of a crucial primary March 18. "Logistical problems are upsetting, but I'm sure they're short-termed," said Bush press aide Susan Morrison.

"This has been a whole new ball game for us, logisticaly. All of our focus has been on political organization and fund-raising. We just have not had to have logistical experts before. We need more bodies."

Bush's Iowa victory made him a hot property in Illinois as elsewhere.About 600 persons braved the snow to have breakfast with him yesterday in Champaign. When his wife, Barbara, saw the overflow crowd, she grabbed his arm, saying, "I want to bask in the glow."

Wednesday night, an even larger crowd of 1,500 attended a fund-raising dinner in Chicago that was expected to raise more than $230,000, making it Bush's most successful such event to date.

Bush has raised a total of $920,000 in January, $330,000 more than he had originally hoped to. In an interview, he attributed the fund-raising success to his Iowa victory.

"It has changed our campaign fundamentally. The thing I worry about now is I don't want to become an instant bigshot."