By Andrew Seidman, The Philadelphia Inquirer (TNS)

Republican presidential front-runner Donald Trump unleashed a fusillade of attacks on rival Gov. Chris Christie on Monday, criticizing him on everything from New Jersey’s economy to the George Washington Bridge scandal.

Trump’s remarks came in response to an editorial written by the publisher of the New Hampshire Union-Leader, which called the celebrity real-estate mogul’s campaign “an insult to the intelligence of Republican voters.”

Trump accused Christie — who was endorsed by the Union-Leader and is gaining ground in Granite State polls — of encouraging the publisher, Joseph W. McQuaid, to write the editorial.

“This is the way Chris is,” Trump said in an interview with WMUR, a New Hampshire TV station.

McQuaid is “backing Chris Christie and it’s ridiculous to back Chris,” Trump said, declaring New Jersey was the “worst state in the union in terms of economics.”

Trump pointed to New Jersey’s high taxes and nine credit downgrades that Wall Street ratings agencies have issued to the state’s debt since Christie took office in 2010, echoing a criticism former Florida Gov. Jeb Bush recently made.

Christie has boasted of vetoing tax hikes passed by New Jersey’s Democratic-controlled Legislature and argued that the state was worse off before he took office.

Unprompted, Trump also recalled Christie’s greeting of President Barack Obama in 2012 when Hurricane Sandy hit the Jersey Shore on the eve of the presidential election — an episode that roiled conservatives.

“He was so warm, and so happy to have Barack Obama in the state of New Jersey that I personally think it could have cost (Mitt) Romney the election,” Trump said.

Upon seeing Christie interact with Obama, Trump said Monday, he even thought Christie “was going to vote for Obama.”

A spokeswoman for Christie’s campaign didn’t respond to a request for comment.

Kentucky Sen. Rand Paul reprised that line of attack in the first GOP debate in August, accusing Christie of giving Obama “a big hug.”

Christie’s record in New Jersey had gone mostly unnoticed during the campaign until recently, as the governor started to climb in the polls in New Hampshire, which holds the first primary on Feb. 9.

On Monday, Trump also declared it was “impossible to believe” Christie “didn’t know about” the George Washington Bridge lane closures in September 2013. Trump has suggested as much before.

“Chris can’t win because of his past,” Trump said. “I don’t believe you’ve heard the last of the George Washington Bridge, because there’s no way he didn’t know about the closure of the George Washington Bridge, and all of his people are now going on trial in the very near future. And they’re going on criminal trial. There’s no way he didn’t know about it.”

Prosecutors say three former Christie allies closed lanes to the bridge as part of a conspiracy to punish the Democratic mayor of Fort Lee, in Bergen County, because he didn’t endorse the governor’s re-election.

One has pleaded guilty and is cooperating with the government. Two others have pleaded not guilty; their trial is scheduled to begin in April.

Trump attacked Christie even as he lobbed insults at McQuaid, “a real low life.”

McQuaid didn’t respond to a request for comment.

Trump said McQuaid in the past had asked him to play golf, eat lunch with him at his country club, and place ads in his newspaper.

In addition, McQuaid requested a “strange thing,” Trump said. When Christie was demoted to the so-called undercard debate in November, Trump said Monday, McQuaid asked Trump to tweet that Christie belonged on the main stage. (This alleged request came before the newspaper endorsed Christie for president.)

On Nov. 6, a few days before the debate, Trump tweeted, “I think it would be a good idea — and fair — to include @GovChristie & @MikeHuckabeeGOP in the debate. Both solid & good guys. @FoxBusiness.”

©2015 The Philadelphia Inquirer. Distributed by Tribune Content Agency, LLC.

Photo: Republican U.S. presidential candidate Governor Chris Christie speaks during the Republican presidential debate in Las Vegas, Nevada December 15, 2015.    REUTERS/Mike Blake