Credit: Joseph Sinnott/NJTV/AP Photo

MONTCLAIR, N.J. - Republican Gov. Chris Christie was front and center at a debate tonight among the Democratic candidates for the open Senate seat in New Jersey, with Newark Mayor Cory Booker's opponents attacking him for his apparent friendship with the governor.

Booker, the frontrunner in the race, countered that his relationship with Christie was a reason New Jersey voters should send him to Washington.

The Newark mayor, who skipped the last debate, said he "found it surprising" that his three Democratic opponents, Rep. Rush Holt, Rep. Frank Pallone, and state Assembly Speaker Sheila Oliver, "counted as a criticism that I worked with Gov. Christie" and instead stressed how his ability to work across the aisle would make him a more effective U.S. senator.

"The truth is he and I disagree on most everything from marriage equality frankly to the issue of giving women access to preventative care, but despite our differences, I am the mayor of the largest city in the state, I've got to work with the governor to get things done," Booker said.

"He and I have partnered together … that's what you've got to do as a United States senator," he said. "You've got to find ways with people you disagree with not to criticize and yell at them, but find ways to reach across the aisle, find common ground where it exists, even if is only 10 percent of the things between you actually make progress."

Booker pointed to his ability to work with Christie as evidence that he could help bring change to Washington.

"If you like what you are getting from Washington stick with it, but it's not working," he said. "If you want the same experiences in Washington take the same experience, but what I think we need in Washington is a different type of experience not more Washington experience."

Earlier in the debate, Booker also mentioned his relationship with Christie, saying the governor is someone who he "disagree[s] with on most issues, but we work together as part of a coalition."

Booker has campaigned with Christie's Democratic gubernatorial opponent Democratic state Sen. Barbara Buono, but he has a famously chummy relationship with the governor. The two even starred in a spoof video in 2012 playing off their friendship across party lines and what was at that time believed to be Christie's vice presidential possibilities.

Pallone jumped on the reference, saying Christie, a possible 2016 presidential candidate, has been "taking money away" from Newark.

"Mayor Booker talked favorability about Gov. Christie's economic program or something, how it benefited the city of Newark," Pallone said. "The fact of the matter is that Gov. Christie has been doing the opposite. … I believe the federal government should help, but the governor is not doing that."

Pallone went on to jab Booker for supporting and working with Christie on education reform in the state, but other than those interactions the four were surprisingly cordial.

Booker even said at one point, "I think there is a lot of agreement here tonight," and he called Pallone a "good and noble person who has worked really hard."

There was some sniping, with Holt saying in his opening remarks that he has "never run into a burning building," teasing Booker for his rescue of a neighbor from a house fire last year, which earned him "hero" headlines.

Holt added that, unlike Booker he doesn't have "one million Twitter followers" and isn't "friends with Mark Zuckerberg."

Oliver also noted that she did not know how "Mayor Booker feels about it because he wasn't at the last debate," but the rest was surprisingly agreeable.

Polls have found Booker holding a wide lead in the race. A Quinnipiac poll from last month showed Booker with 52 percent, Pallone with 10 percent, Holt with 8 percent, and Oliver with 3 percent.

Holt was also relatively easy on Booker, despite releasing a television ad Monday hitting the Newark mayor and saying he might be the frontrunner, but he is "no progressive."

The debate, held at Montclair State University, was the first to feature all four of the candidates and also touched on the NSA surveillance programs, the United States' relationship with Russia, school voucher programs, and the Affordable Care Act, among other issues.

The primary for the seat vacated by Frank Lautenberg's death in June is scheduled for Aug. 13. The winner will most likely go on to face Republican businessman Steve Lonegan.