NEWARK - A tweet sent out by senatorial candidate Steve Lonegan’s campaign has prompted a response from frontrunner Corey Booker.

A campaign staffer for the Republican tweeted a map of Newark, with hand-drawn labels for various parts of the city, including West Africa, the Middle East, Afghanistan and Pakistan. It was up for less than 10 minutes before being deleted.

The tweet was seen as an attack on Newark Mayor Cory Booker, the Democratic frontrunner.

"Lonegan campaign's tweet is inappropriate, offensive and fundamentally out of step with New Jersey values."

Lonegan dismissed the tweet, calling it “silly and childish.” He says the staffer was disciplined for his actions.

The latest polling numbers show Booker beating Lonegan in the special election for the Senate seat vacated by the late Sen. Frank Lautenberg.