ATLANTIC CITY — As a cocktail waitress for 27 years in this city’s Xanadu of a casino industry, Valerie McMorris learned the hard way that Donald Trump’s art of the deal too often proved to be the art of bankruptcy. “I’ve been through three bankruptcies with Mr. Trump,” she said, recalling how the fast years of gambling growth here degenerated into a crushing excess of casinos. She watched as Mr. Trump hurried to remove “TRUMP” from the facades of suddenly failing casinos, lest they undermine his claims to financial invincibility.

The self-branding mania that has helped Mr. Trump earn his victory as the presumed Republican candidate for president has not worked here. Ms. McMorris, a union representative for Unite Here Local 54 of the city’s casino workers, is fascinated by how his political winning streak plays out just beyond a battered Atlantic City, a destination once identified with Mr. Trump that serves now as a reality check. His name has disappeared from three casinos, one of which has closed. Across the city, casino workers have lost pensions and health care in bankruptcy proceedings, and four of 12 casinos closed in recent years, with thousands of jobs lost. Home foreclosures are multiplying and the city has suffered such a precipitous loss in revenue that the state is threatening a takeover.

“Carl Icahn as Trump’s secretary of the Treasury?” Ms. McMorris asks with alarm of Mr. Trump’s billionaire ally, who has been mentioned as a possible cabinet choice in a Trump administration. Mr. Icahn owns the Trump Taj Mahal, the one place where Mr. Trump’s name remains prominent, and has been keeping the casino afloat since it filed for bankruptcy in 2014, in part by eliminating union benefits.

There is a memorable line in the movie “Atlantic City” when Lou Pascal, the aging hoodlum go-fer played by Burt Lancaster, celebrates the beachfront city’s simpler past of tourists and gangsters: “You should have seen the Atlantic Ocean in those days.” But there seemed a glimmer of Lou’s wistfulness on Monday when Senator Bernie Sanders came to town to campaign before New Jersey’s June 7 primary. With Local 54’s endorsement in his pocket, Mr. Sanders delighted a crowd with a thumping attack on Mr. Trump and Mr. Icahn as enablers of “the ugliness and the greed that we’re seeing all over this country.”