This slow trip on the muddy Mississippi may go down as the strangest journey of Jimmy Carter's presidency.

When passengers on this old, wooden sternwheeler went to bed after midnight last night, groups of people around campfires on the river banks were still yelling, "Hey Jimmy, Hi Jimmy. Hello Jimmy."

Today, at 6:10 a.m., the president of the United States was jogging past their staterooms. He circled the deck 22 times, or about two miles, waking many of the 180 people aboard.

Carter seems to relish it all. He waves to drunks on passing boats. He mingles with passengers, pointing out the location of the Big Dipper and the North Star.

And when a young couple from Parker, S.D., strolled by last night wearing T-shirts reading "We are honeymooning on the Delta Queen," the president told them:

I hope I can keep people occupied so they don't spend all their time watching you."

Washington, Andy Young, the economy and Carter's reelection problems seemed light years away as the sternwheeler eased down the winding river. The only newspaper the president read this morning was the Wabasha County Herald. "The president of the United States is coming to Wabasha County!" it gushed, promising that 20,000 people would greet the president and his wife Rosalyn for a prayer service.

Wabasha, Minn., (population 2,300 was scheduled to be only a stop for water. But Carter joined the service anyway.

Only about a third of the 20,000 people showed up. But there was a band, a birthday cake to celebrate Mrs. Carter's 52nd birthday and a cool breeze off the river. The Carters plunged into the crowd for more than 30 minutes, shaking every hand in sight.

It's that kind of a trip, relaxed, loose, free and easy.Carter is probably more accessible to a group of ordinary citizens than at any time since his inauguration.

Passengers and a handful of reporters on board the 53-year-old Delta Queen didn't know how to act. After all, what do you say to the leader of the free world when he's standing in his jogging shorts with sweat pouring from his brow at 6:30 a.m.?

Mostly people talk about the weather. (It's beautiful.) or river traffic. (Carter seems to know a great deal about cargo barges). And whether or not the president will get one of his two fishing poles out later in the day.

"Our conversation was mostly small talk," said John Works, a retired savings and loan officer from St. Paul, where the boat pushed off from last night. "He showed us where the North Star and the Big Dipper ; are. We mentioned we have a very serious situation in Duluth with a strike stopping grain shipments and we hoped he could do something about it.

"Then, we ran out of things to say."

Carter is making this seven day trip from St. Paul to St. Louis to vacation and to plug his energy program.

Normally, there isn't too much energy on this boat, the last of the wooden, overnight paddlewheelers so common on this river a century ago. It caters to nostalgia buffs and the older set. Highlights from the list of "steamboatin' activities" and official guide books are checkers, shore gazing and an afternoon singalong in the Texas lounge, the best bar on board.

Earlier this week, there were television reports that the Carters would find the Delta Queen a "love boat" because there were so many unmarried couples sharing staterooms. That was baloney.

Most of the passengers are middle class families or retirees; many are widows. And when Vic Tooker and the River Boat Ramblers, the boat's honky tonk band, tried to get things stirred up a little last night in the Orleans Room, they gave up after half an hour. "When the band is bigger than the crowd, it's time to quit," Tooker said at 11:30.

Larry and Mary Jo Miller, married one week ago, are the most noticeable lovers aboard. He is one of the few people unawed by the president. "It didn't bother me one bit talking to him," he said. "He puts his pants on just the same as me -- one leg at a time."

Carter, his wife, Rosalynn, and daughter, Amy, are staying in staterooms 339 and 340 on the sun deck. They're the largest, plushest rooms on the boat but they're still relatively modest and compact; together the two rooms are smaller than a single room in a typical Holiday Inn. They also have the best view on board -- in effect, a third story view over the stern. But the location carries a disadvantage, for the rooms are located between the calliope and the paddlewheel and may be the noisiest on board.

The John Works and the John Bakers of St. Paul were to occupy the two staterooms at a cost of $980 per couple (that includes plane fare from St. Louis, where the trip ends, back to Minneapolis.)

They were bumped two decks down.

"At first we weren't terribly thrilled about the Carters coming on board. We're all pretty good Republicans," said Mrs. Works.

"But when you look around at the other passengers you realize it would be pretty dull here without the Carters and the people they brought with them," she added.

The passengers here aren't particularly political. Nor are they necessarily Carter supporters. Rather, they are a mixture of retired schoolteachers, Midwest dentists, widows and middleaged businessmen -- the kind of people Carter might meet at a convention of Rotarians.

Almost everyone bears some message for the president from the people back home.

Mrs. Gertrude Nelson, of Janesville, Wis., handed the president a letter for Amy from her 12-year-old grandson. "I don't know what it says, he's just hoping Amy will write back," Mrs. Nelson said.

Others have been instructed to bring back piles of autographed pictures. "One of my friends told me 'When you get near him, push him overboard,' " said Lillian Folta, of Upsala, Minn., population "380 and growing."

The passengers know Carter is in political trouble, and that they in effect are stage props on this trip. That doesn't seem to bother most. "I've never really been for him," said John Baker, the owner of a chemical manufacturing company in St. Paul. "But we're developing some sympathy for him. Everyone has been piling on him so hard. He needs some friends."

He and his wife, Elizabeth, were wearing T-shirts that said, "I went down the river with President Carter."