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.