Former Vice President Joe Biden offered praise for Phil Murphy at an appearance with New Jersey's Democratic gubernatorial front-runner Sunday, calling the off-year election the most important in the country over the next three years.

Murphy is leading the pack in the Democrats' June 6 primary and has a huge campaign cash advantage over his three leading rivals as he bids to succeed Republican Gov. Chris Christie.

In front of about 1,000 people at a community center, Biden said the country — and world — will be watching the election "to decide whether or not America has bought into this crass and mean spirited and negative and uncomfortable rhetoric that we have been subjected to these last 10 months — or whether (we are) ready to re-establish and assert who we are."

Murphy served under President Barack Obama as ambassador to Germany. He has loaned his campaign more than $15 million and has spent about six times more than his rivals combined.

Biden revealed that he flew to Germany five years ago to try to convince Murphy to run for office, though he didn't say which office. He said late Democratic Sen. Frank Lautenberg urged him to try and recruit Murphy.

Murphy's deep pockets notwithstanding, Biden focused on the two men's working-class Irish roots and said he trusts Murphy's "gut." He also scolded Democrats for not speaking to the fears and aspirations of the middle-class, something he said President Donald Trump exploited in the 2016 election.

Murphy said he will stand up to Trump with "a steel backbone," and criticized the president for proposing tax cuts for the wealthy.