In one notably feisty exchange, Booker, the mayor of Newark, said Lonegan, a conservative activist and former Bogota mayor, would want to gut environmental regulations, using the polluted Passaic River as an example of the need for them.

"You may not be able to swim in that river, but it’s probably, I think, because of all the bodies floating around of shooting victims in your city," Lonegan shot back.

"Oh my God," Booker said.

In another exchange, Lonegan said the state has poured countless dollars "into a big black hole in Newark."

Booker called Lonegan’s tone "insulting" and, in a theme he repeated throughout the debate, said Lonegan needed to stop "talking down to New Jersey’s cities."

"We’re one state with one destiny," Booker said.