WASHINGTON (AP) _ Jean Diemunsch says she sometimes wakes with a start in the middle of the night, wondering if Bruce Babbitt got to where he was going, and whether he got there on time.

The whereabouts of the former governor of Arizona might seem like an odd thing to ponder in the predawn hours.

But Diemunsch is a campaign scheduler for Babbitt, who is seeking the Democratic presidential nomination.

She says her job is something of a contradiction in terms - because schedules and campaigns often just don't seem to go together.

''I think it's a law of physics,'' Diemunsch says. ''Where you have a presidential candidate, you have a certain amount of built-in chaos.''

The people who put presidential campaign schedules together, weeks or months in advance, say they constantly cope with enormous changes at the last minute.

''We had to charter a private jet to get him back in time for a vote,'' says Dick Deerin, chief scheduler for Sen. Albert Gore Jr., D-Tenn.

''You realize people want him in two places at the same time,'' says Hasper, an assistant scheduler for Rep. Jack Kemp, R-N.Y. ''Or more than two.''

''He was stuck on the ground for hours in a plane at O'Hare,'' recalls Richard Sullivan, who helps schedule Rep. Richard Gephardt, D-Mo. ''And once we forgot about the time difference between El Paso and the rest of Texas.''

The schedulers say they get used to seeing a perfectly mapped-out schedule fall to pieces. They can go crazy, they say, or be philosophical.

''It's a juggling act, and it never stops,'' says Teresa McManimon, who works for Republican Alexander M. Haig Jr.

''It's never like clockwork, but you cope,'' says Deerin of the Gore campaign.

The schedulers say conflicting demands continually pile up. At any time, says Hasper of the Kemp campaign, there are 500 or 600 pending invitations. That's a lot of RSVPs.

Most schedulers say they quickly learn things like what airports to avoid or what types of events will invariably run long. Diemunsch says she knows the backroad routes to tiny towns in New Hampshire she hadn't heard of a few months ago.

But knowing the tricks of the scheduling trade won't necessarily make things easier as the campaigns move into the crunch time leading up to the Iowa caucuses and the New Hampshire primary.

In fact, the coming months will bring more delays caused by winter weather, and the campaign entourages will get bigger. Both those things mean more scheduling complications.

''It's kind of thankless, because when things go right, no one thinks about the schedule,'' says Sullivan. ''Then something goes wrong, and the sharks start circling.''

Nobody likes to break the bad news when the candidate is running late for a steak fry or isn't going to make it to a county fair. But it's a task that frequently falls to the hapless scheduler.

''I just try to be as honest as I can, and let people know we're trying our best to get him there,'' says Elizabeth White of Pete du Pont's campaign. ''Ninety-nine percent of the time, they're really understanding.''

The schedulers like to talk about how nerve-racking their work is. But they also tend to say they wouldn't want to be doing anything else.

''It's really rewarding,'' Sullivan says.

''It's invigorating,'' says Hasper.

''I can't talk now,'' says Eileen Maroney, a scheduler for du Pont. ''I have a schedule to get out.''