In any given summer, the Hamptons are transformed into an A.T.M. for national politicians, particularly Democrats who are running for president.

This year, the moneyed parts of Long Island have become a 24-hour bank machine for one campaign in particular.

“There’s no question about it,” said corporate P.R. man Morris Reid. “Hillary Clinton owns the Hamptons.”

Or as local bookstore owner Charline Spektor put it, “She’s part of the landscape of what goes on here.”

That much is true—thanks to a certain surrogate named Bill Clinton—even when the candidate isn’t actually present.

At around 9:30 on the night of Friday, Aug. 3, for example, four SUVs rumbled up the driveway of Mr. Reid’s East Hampton home. By then, news that Mrs. Clinton was a no-show had long since sunk in for the roughly 200 people who had paid between $250 and $1,000 to gather in Mr. Morris’ backyard.

Once Mr. Clinton took up his position in front of the crowd, it hardly mattered.

Mr. Reid, co-founder of the P.R. firm Westin Rinehart, gave the introduction. “You guys are all here and we appreciate that, but we want you to dig deep—we need you to dig deep,” he said to a rapt, heavily female audience. “We are in a time where money counts in politics. It’s a shame, but it’s a reality. We’re in the Hamptons, we can all afford to write checks.”

Mr. Reid continued: “Bill Clinton created more millionaires in his terms than any president in history. You guys need to be more enthusiastic about fixing the economy.”

The crowd broke into applause.

Moments later, the former president took the microphone.

“You probably know by now that she’s not here,” said Mr. Clinton, who looked unusually thin and Hamptons-spiffy in a linen blue blazer, khakis and tan loafers, and who had already played surrogate earlier that evening at a fund-raiser at the Southampton home of Irene and Bernard Schwartz. “I want to explain what happened. I got a call tonight a couple of hours ago. She was in the plane. She said, ‘I’m in the plane.’ She said, ‘I’m all dressed up and I look really nice.’”

He went on to explain that his wife had been held up in Washington by a Senate vote. And judging by the crowd’s rapturous reaction, that was enough.

As the recently concluded whirlwind tour of Long Island’s toniest towns—seven events in three days—once again made clear, no other campaign has the moneyed Hamptons at its disposal quite like the Clintons do.

“I don’t think anyone was disappointed,” said Tina Waksman, who attended the event at Mr. Reid’s home. Mr. Clinton, she said, had “cast a spell” on everyone.

Over the course of the weekend, Mr. Clinton would go on to do his bit at a Saturday afternoon cocktail rally at the home of Dottie Herman, president and CEO of Douglas Elliman; at the mega-dinner that night hosted by Revlon poobah Ronald Perelman; and again at a celebrity pancake breakfast at the home of financier Alan Patricof.

Mr. Reid began working for Mr. Clinton on the 1992 election campaign as a field operative in Ohio, and went on to serve as a senior advisor to Secretary of Commerce Ron Brown.

“Bill was in his Elvis mode last night, he was a rock star,” he said, tucking into a plate of French toast on Saturday morning at Babette’s, a fashionable eatery-salon in East Hampton.

He boasted that his event, and Bill Clinton, had raised roughly $200,000 for Hillary Clinton.

He said he told Mr. Clinton, “You’ve got it,” and the former president replied with something along the lines of “Aw, shucks.”

Star Jones, who had a front-row seat at the Reid party—and who at one point leapt at a chance to pose for pictures with Mr. Clinton—had a similar impression.

“There is no politician before or since that makes a crowd of people, friends and foes, giddy with enthusiasm just to be in his presence,” she said in an e-mail after the event. “I know that Hillary is ready to lead this nation the day she takes office, clearly there is no one more qualified. But it is good to know that my favorite president has that same passion and enthusiasm for her candidacy.”

On Saturday, at another solo mission—this at the Hermans’ house in Southampton—he again had to excuse his wife’s absence, this time because she had been delayed in Chicago at the YearlyKos event, according to Ms. Herman.

“He said he could best help behind the scenes, going around and really helping restore—because he’s popular around the world—he said he would be best behind the scenes helping to restore the confidence in the U.S. and building that relationship up again,” recalled Ms. Herman, who describes herself as a registered Republican who doesn’t vote along party lines.

The hostess said that, over the course of a brief speech and a question-and-answer session, the would-be First Man spent roughly the same amount of time talking about his wife as he did about himself.

“Pretty much, whatever you asked him, he was very comfortable and he answered anything that was asked about him,” she said. “He was great. He really took his time.

“As a matter of fact,” she continued, “we had the Secret Service, and they were like, ‘Dottie, talk to him and tell him that’s the last question, he’s got to go.’” She laughed. “I mean, they were really trying to get him off, and he kept on taking more and more questions. And then finally I had to break in and say, ‘Listen, he has another affair and he’s late.’”

Mr. Clinton, she noted proudly, took one of her fresh baked pecan pies for the road.

The very important subsequent engagement was across town in East Hampton at Mr. Perelman’s place, where Mr. Clinton was at last joined by the actual candidate.

According to accounts from several attendees, Mr. Clinton assumed a completely different role in her presence. At the cocktail hour—price tag $1,000—which took place on Mr. Perelman’s sprawling patio overlooking Georgica Pond, Mr. Clinton blended in with the crowd, mingling demurely with Jon Bon Jovi, Donna Karan, Calvin Klein, Chevy Chase, Russell Simmons, Brett Ratner, Harvey Weinstein, Barry Diller and Diane von Furstenberg. Chuck Schumer and Harold Ford Jr. and Sr. were also in attendance.

Mr. Clinton made some brief remarks before Senator Clinton, clad in a bold turquoise jacket and matching blue jewelry, gave her speech. Her husband stood quietly by her side.

“You definitely knew who the candidate was in the room,” said Mr. Reid, who attended the party.

The dinner portion of the event—attendance, $4,600—was given in the “farmhouse,” a giant amphitheater with a professional-grade sound system.

It was a similar scene the following morning at the Patricof pancake feast, which was, according to sources, attended by roughly 500 people paying $500 a head.

Mr. Clinton, wearing a polo shirt with the presidential number “42” on it, limited himself to a short introduction.

“He definitely played the role of supportive husband,” said one man who attended the Patricofs’ pancake fund-raiser.

Barbara Layton, the politically active owner of Babette’s, noted that it is “very evident” that Hillary Clinton “holds her own” at gatherings like the one she attended at Mr. Perelman’s.

That isn’t always the case.

On Sunday, while Mrs. Clinton attempted a quick shopping venture at Roberta Freymann on Newtown Lane in East Hampton, her husband stopped into Ms. Layton’s restaurant.

“Bill walked in and the place went into an uproar,” said Ms. Layton. “An uproar. And it was so funny, because I thought they were both coming in, and everybody was standing in their seats and on their chairs, and I said, ‘The next president of the United States is about to walk in’—and in walks Bill Clinton,” she recalled, with a laugh. “And everybody was delighted. He just came in, he worked the room. Everybody was clapping. And he came into the kitchen, tasted one of the sweet potato fries, and I said, ‘Do you want to take one with you?’ And he said, ‘Yeah, wrap them up for me.’ So I wrapped up the sweet potato fries for him and walked him out. And everybody was just all over him outside, like it was the first day, like it was back in 1998.”

One almost gets the impression that it’s the sort of thing Bill Clinton might enjoy. But, to hear him talk about it at the fund-raiser on Friday night, he’s just doing his duty.

“I want you to believe that if we were not married and Hillary asked me to leave Chappaqua, New York, and haul myself down to Long Island and be at this event tonight and speak for her or do anything else, I would do it,” he said. “Because I believe by far that she is the best qualified person.”