Even as a joke, Brooklyn Borough President Marty Markowitz wasn’t willing yesterday to buy into Mayor Bloomberg’s concerns about landing another job after he leaves City Hall.

“Marty and I are going to lose our jobs in 679 days,” the mayor announced as he introduced the Beep at a press conference about a new jobs center inside the Brooklyn Public Library.

“I have a hunch one of us will actually be looking for a job in those six-hundred-something days,” responded Markowitz.

“That’s me,” interjected the mayor.

“Oh, sure,” came back a skeptical Markowitz.