New York power brokers, including Sen. Chuck Schumer, Joe Lhota, David Dinkins and Ray Kelly, arrived at Park Avenue Winter at the crack of dawn yesterday when the restaurant officially inherited the Loews Regency’s daily power breakfast. Holding court at a corner table with his stylish wife, Lizzie, Loews chair and Giants co-owner Jonathan Tisch told us he cooked up the temporary relocation at 4 a.m. one morning. “I don’t sleep,” he explained, “I write notes.” (A signature power move.) “Some of our regulars, people who come here every day, were literally crying” because the Regency would temporarily close, Tisch explained, not naming names. “We live in a pop-up world, so why not a pop-up power breakfast?” Other unfeasibly fresh-faced machers packing the place at 7 a.m. included Bloomingdale’s CEO Michael Gould, real-estate honcho Billy Rudin and Alexandra Lebenthal. By 9, the room was empty after they’d all left to run the city. Proving eggs and French toast cross party lines, Lhota and Dinkins rubbed elbows by a buffet. A spy caught a glimpse of a “secret box” in a back room, where picky power players keep treats not on the menu. Amid the stash of granola and matzo, Larry King kept a bag of Kevin Garnett’s favorite cereal, Honey Nut Cheerios.