EAST HAMPTON, N.Y. – A woman in a blue chiffon dress poked her head out of a black Range Rover here on Sunday afternoon and yelled to an aide to Mitt Romney, “Is there a V.I.P. entrance. We are V.I.P.”

No such entrance existed. The line of cars waiting to enter a Romney event at a waterfront estate here had reached 30 deep, testament to the Republican candidate’s fund-raising might on a weekend when he is expected to haul in $3 million in the Hamptons.

Mr. Romney’s aides apologized for the wait: each donor had to be checked off a guest list in the driveway, leading to a major backup. “We are doing our best,” an aide carrying a clipboard said, sweat dripping down her cheeks.

Mr. Romney arrived in this town of outsized homes and conspicuous consumption for the first of three major fund-raisers on Sunday afternoon, his motorcade of Chevrolet Suburbans passing a gleaming line of Bentleys, Porsches and a Mercedes Benzes waiting to deposit guests who paid up to $25,000 a head to hear him speak.

A luncheon fund-raiser was held at the sprawling home of Ronald O. Perelman, the billionaire financier and chairman of Revlon. Widely described as the largest estate in East Hampton, it has 40 rooms, nine fireplaces and takes up a mile along Georgica Pond.

After that, Mr. Romney, a former Massachusetts governor, was also scheduled to attend fund-raisers at the Hamptons homes of Clifford Sobel, the former United States ambassador to Brazil, and the billionaire industrialist David H. Koch, a major donor to conservative causes.

The event at Mr. Koch’s home, the biggest of the day, was expected to attract a sizable crowd of protesters, who, in brochures promoting the demonstration, said they opposed “the ever-growing and pervasive influence of Koch Industries,” the company controlled by Mr. Koch and his brother, Charles.

At Mr. Perelman’s house, a handful of guests stuck in the line outside rolled down their tinted windows to chat or simply shouted from their convertibles of their enthusiasm for Mr. Romney and disdain for President Obama.

Laura R. Schwartz of New Jersey, the woman inside the Range Rover, complained that Mr. Obama had not visited Israel as president, a slight to the country, in her eyes. “I don’t think he is good for Israel,” she said. Mr. Romney, she said, “is a fresh face.”

A few cars back, Ted Conklin, the owner of the American Hotel in Sag Habor, N.Y., long a favorite of the well-off and well-known in the Hamptons, could barely contain his displeasure with Mr. Obama. “He is a socialist. His idea is find a problem that doesn’t exist and get government to intervene,” Mr. Conklin said from inside a gold-colored Mercedes as his wife, Carol Simmons, nodded in agreement.

Ms. Simmons paused to highlight what she said was her husband’s generous spirit: “Tell them who’s on your yacht this weekend! Tell him!”

Over Mr. Conklin’s objections, Ms. Simmons disclosed that a major executive from Miramax, the movie company, was on the 75-foot yacht, because, she said, there were no rooms left at the hotel.

In Southampton, where Mr. Koch lives, the local police spent much of Sunday gearing up for as many as 200 protesters, a rare sight in these precincts. It would be “the first large-scale protest” the village has ever had, Chief Tom Cummings said.

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The packed schedule of fund-raisers seemed to create some confusion among the guests. As he pulled up outside Mr. Perelman’s estate, Ms. Schwartz’s companion initially wondered if he was the home of the Koch brothers.

Oh, he said, not yet.

“We are going to all of them,” Ms. Schwartz explained.

Michael Barbaro reported from East Hampton, and Sarah Wheaton from Southampton.