Senator Frank Lautenberg took the opportunity during his speech at the New Jersey Chamber Of Commerce's dinner in Washington on Thursday night to make another dig at potential 2014 challenger and Newark Mayor Cory Booker.

Cory Booker addresses the NJ Chamber Of Commerce Ride To Washington breakfast in Newark (Gellman Images)

"I'm disappointed that Cory Booker couldn't be here tonight. I'd think spending time out of the city was one of his favorite activities. Perhaps we were too close to Newark," said Lautenberg according to buzzfeed.com.

The dinner was the culmination of the Chamber's annual train ride to Washington which began in Newark with a breakfast addresses by Booker.

It's the latest comment about Booker made by the 89-year-old Senator who is up for re-election in 2014. Booker announced his intention to run for the seat in December via video and the formation of a campaign with the Federal Election Commission. However, after Democrats and Lautenberg advisors started making negative comments, Booker backed away from a campaign telling David Gregory on NBC's Meet The Press it was "premature" to say he was definitely running

Lautenberg himself has said that Booker has got a lot of work to do (in Newark),  a lot of work that should have been done  and hasn’t been done.” He also joked  told the Philadelphia Inquirer of Booker’s challenge, “”I have four children, I love each one of them. I can’t tell you that one of them wasn’t occasionally disrespectful, so I gave them a spanking and everything was OK.”

Fox News host Geraldo Rivera on his radio program on Thursday announced that he is seriously considering a run for the seat in 2014 as a Republican.

Listen to Rivera's comments about running in 2014