Cory Booker in The Wall Street Journal

On Energy & Oil: Has never taken a public position on a carbon tax

A Booker campaign spokesman questioned the ad's validity, saying the mayor has never taken a public position on a carbon tax or breaking up banks. "It's disappointing that Representative Holt would mislead voters about Mayor Booker's record," he said.

Booker launched his fourth ad Monday, with the mayor speaking about what he would bring to the Senate while ignoring the other primary candidates.