Michael Bloomberg took a dig at President Trump's obsession with building a border wall as he unveiled an infrastructure plan before a conference of mayors.

The former New York City mayor, 77, who routinely pokes fun of Trump's real estate career, slammed the president's track record on infrastructure.

"What's he delivered? Nothing," Bloomberg told the winter meeting of the U.S. Conference of Mayors in Washington, D.C., to laughs from the crowd. "There seems to be only one construction project that he cares about, and it's a border wall that is a political gimmick and a costly one."

Bloomberg, a late entrant into the 2020 Democratic presidential primary who is focusing on Super Tuesday states, similarly swiped at his rival's infrastructure proposals for being preoccupied with money rather than initiatives. The billionaire media mogul's platform includes streamlining cities' access to funding and ways to meet environmental requirements.

"Most don't have any experience in managing big infrastructure projects," he said. "Mayors understand that money is only part of the problem."

Bloomberg described his campaign as a smaller-scale conference of mayors, with three city executives advising him, including Michael Tubbs of Stockton, California, which he seemed to mispronounce "Stubbs" accidentally.

"You will have a seat at the table in ways that has never happened before," he told the audience, touting cities as policy labs and inviting those in attendance to join his "unofficial kitchen cabinet."

He added that he "loved" his three terms leading New York City.

"I would urge all of you to do 12 years. And if you have minor problems with limits, change the law," he joked, referring to how he asked the New York state legislature and governor to allow him to remain in charge past the eight-year limit.