So Mr. Bergdoll, the country s most entertaining John Travolta impersonator, as his Web site, briantravolta.com , has it, hustled down 40th Street in Manhattan, his white bell-bottoms flashing beneath his trench coat. He was scheduled to perform at a Christmas party in Caldwell, N.J., on Saturday at 6:55 p.m. The bus was leaving from the Port Authority terminal in less than 12 minutes. This happens all too often to Mr.

Bergdoll, a garrulous 36-year-old who bears a sort-of-maybe resemblance to Mr. Travolta and who, by his own admission, is prone to distraction. But a man who makes his living dancing at crowded parties in tight polyester suits is not afraid of sweat. Mr. Bergdoll broke into a sprint. Christmas is the party season, and the agencies that book impersonators and other entertainers are doing serious business.

Hannah Montana is hot this year for the teenage parties, said Jim Rothwell, a manager of Best Entertainment Around, the New Jersey agency that did the booking for the party in Caldwell. Austin Powers continues to be in demand, as is Joan Rivers . Rod Stewart is enjoying an odd resurgence and, as always, anybody who can do a sitting president is making bank. But Elvis Presley and Marilyn Monroe are perennials, as is Tony Manero, Mr. Travolta s character in Saturday Night Fever.

The week before, Mr. Bergdoll performed at a corporate event in Philadelphia and the week before that, at the 28th annual World s Largest Disco, a benefit in Buffalo. This year the headliner at the Disco was Erik Estrada of CHiPs, but to celebrate Saturday Night Fever, which will turn 30 on Sunday, Karen Lynn Gorney (who played Stephanie Mangano) reprised the dance contest scene with Mr. Bergdoll. How, exactly, does one find oneself in this line of work? I ve had a lot of random jobs, Mr.