TRENTON, N.J. — The wealthy front-runner in the New Jersey Democratic primary for governor has spent nearly six times the amount of his five challengers combined.

Election Law Enforcement Commission reports published Wednesday show that Phil Murphy has spent $18 million — most from his own pocket — ahead of the June 6 primary.

His Democratic opponents have spent about $3.25 million combined.

The reports come a day after the first debates in the primary. In the Democratic debate, Assemblyman John Wisniewski and former Clinton administration official Jim Johnson attacked Murphy for using his wealth to influence the contest.

Murphy is a former Obama administration ambassador to Germany and a Goldman Sachs executive.

In terms of spending, Democrat Jim Johnson, who served in the Clinton administration, comes in at No. 2, at $1.7 million.

Republican Lt. Gov. Kim Guadagno has the most cash on hand at $1.5 million.

She has spent $715,845, while her leading Republican opponent, Assemblyman Jack Ciattarelli, has spent $824,510.

Combined, the six Democrats and five Republicans in the race have spent just over $23 million.

Election Law Enforcement Commission executive director Jeff Brindle says candidates spent about $10 million through a similar time period in the 2013 contest. But Brindle added that there were only four candidates then, compared with 11 this year. Gov. Chris Christie was also the leading GOP candidate, with no opponents.

The Democrats are set to debate again on Thursday; Republicans will meet May 18.

The election is in November. Christie is prevented by term-limit laws from running for re-election.