NEWARK, N.J. -- The underdog candidates in New Jersey's Democratic gubernatorial primary sought Thursday night to make the election a referendum on money in politics and the state's notoriously boss-driven political system.

Appearing in New Jersey's largest city for the second and final Democratic debate before the June 6 election, three candidates portrayed the front-runner, Phil Murphy, as the product of that system.

"We have a candidate who has made the system awash in money. It's an obscene amount of money," said Assemblyman John S. Wisniewski, a former state party chairman, who accused Murphy of using his largesse to buy the support of county party leaders. Murphy has won the endorsement of all 21 chairs, as well as a host of labor unions and liberal groups.

Murphy, a former longtime Goldman Sachs executive, has raised $19 million, including $15 million he has personally lent to his campaign, according to records filed with the state Election Law Enforcement Commission (ELEC). He has spent $18.4 million -- the seventh highest total in New Jersey election history, according to an ELEC analysis.

Wisniewski, as well as State Sen. Raymond J. Lesniak and former U.S. Treasury official Jim Johnson, argued that Murphy had won party support -- crucial in a primary -- well before counties held their conventions for official votes among the rank-and-file members.

"The people who showed up to the conventions are good Democrats. They're good progressives," Murphy responded. "These aren't party bosses. These are fellow citizens who are dying to turn the page."

Murphy also said he had invested money to help build the Democratic Party after two terms of  Gov. Christie, a Republican who will leave office in January.

"What I'm hearing," Johnson said, is that "the party has been bought and paid for. It needed strengthening and [Murphy] made the deposits."

The Associated Press reported in February that Murphy had donated about $250,000 to state and county Democratic parties since 2015.

Wisniewski, Johnson, and Lesniak also attacked Murphy over his plan for a public bank, which they argued would be a government boondoggle and patronage pit; what they described as a discrepancy between the recommendations he delivered to the state in 2005 on pension and health benefits and his current positions; and his tenure at Goldman Sachs.

In 2005, Murphy chaired a commission that called, among other things, to raise the retirement age and "make the pension reflect a longer time horizon of an employee's salary."

The pension system is the worst-funded in the nation, according to the Pew Charitable Trusts.

Murphy now says the state, which has underfunded the pension system for public workers for years, must meet its obligations before calling for changes to the system.

"That's the kind of doublespeak we've seen in this campaign," Wisniewski said.

Murphy noted that his 2005 report called on the government to meet its commitments and rejected the criticism. "As a general matter here, we are a state that folks no longer trust," he said.

On other issues, the Democrats generally called for a lot of spending: on pensions, education, health care (Wisniewski championed a single-payer system in New Jersey), and other programs. And they talked about which taxes they would consider raising.

"We've made promises that are extraordinarily expensive on this stage," Johnson said.

The problem with Trenton, he said, was "saying we can do everything" and kicking hard choices down the road.

Murphy also faced attacks over his time at Goldman, which his opponents blamed for the 2008 market crash. How, they asked, could he square his career on Wall Street with his progressive values?

Murphy noted that his 23-year career ended in 2003, before the crash, and defended his tenure at Goldman.

"I did work at Goldman Sachs. That's a chapter in my career," he said, adding that he learned skills that could help create jobs.

"I don't want anyone lecturing me about progressive values," Murphy added, saying he grew up in a working-poor family.

"Progressive values are not a book I have to read or some abstract concept," he said.

Murphy held a sizable lead in the most recent Quinnipiac University poll, but a majority of Democratic voters said they did not know whom they will support in the primary.

Lt. Gov. Kim Guadagno and Assemblyman Jack Ciattarelli, the two leading GOP candidates, are scheduled to hold their final debate on Thursday in Newark.