Take two Republican politicians – one brought up in New York City and one who hails from New Jersey, who are both known for brash and assertive in-your-face politics, and both mulling White House runs in 2024 – and things can get testy.

That’s certainly the case right now between former President Donald Trump and former New Jersey Gov. Chris Christie.

After Trump this week belittled his longtime friend, Christie touted that he’s "never walked away from an argument."

CHRISTIE URGES REPUBLICANS TO ‘MOVE ON’ FROM 2020 ELECTION

The fireworks began this past weekend when Christie, in a speech to an influential group of Republicans and in an interview with Fox News, urged his party to stop looking back to Trump’s 2020 election defeat to now-President Biden and instead "move on and talk about issues that voters care about."

Christie address RJC

Former GOP Gov. Chris Christie of New Jersey addresses the Republican Jewish Coalition's annual leadership meeting, on Nov. 6, 2021, in Las Vegas, Nevada.  (Fox News )

Christie was in Las Vegas on Saturday, addressing the annual leadership meeting of the Republican Jewish Coalition (RJC), a major conference of party leaders, activists, mega-donors and bundlers.

"We can no longer talk about the past and the past elections," the former governor, a supporter of Trump but vocal critic of the former president's litigating of the 2020 election, said to applause. 

"No matter where you stand on that issue, it’s over," Christie argued. "Every minute we spend talking about 2020, while we’re wasting time doing that, Joe Biden and Kamala Harris, Nancy Pelosi and Chuck Schumer are laying ruin to this country. We better focus on that and take our eyes off the rearview mirror and start looking through the windshield again."

Minutes later, Christie warned in a Fox News interview that Republicans "lose if we look backward. We’ve got to go forward, we’ve got to move on. We’ve got to move on and talk about issues that voters care about."

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The former governor’s speech and interview came days after the gubernatorial victory by Republican Glenn Youngkin in Virginia, where the GOP hadn’t won statewide in a dozen years, and after Republican Jack Ciattarelli’s near upset of Democratic Gov. Phil Murphy in the blue state of New Jersey.

"This past Tuesday was the beginning of the new era for the Republican Party," Christie told the crowd. 

And in his interview, he emphasized that "Glenn Youngkin did not have a backward-looking campaign and neither did Jack Ciattarelli. If what we’re going to continue to talk about is the 2020 election and grievance politics, I think you got a market test in Virginia and in New Jersey. And that market test was candidates don’t think that’s going to work. And one of those candidates won, and the other candidate came close in a blue state to winning."

Nearly six years ago, Christie’s presidential run crashed and burned after a disappointing and distant sixth-place finish in New Hampshire’s presidential primary, where he’d placed all his chips. Christie quickly backed Trump, who had crushed the rest of the field in New Hampshire, launching the real estate mogul and reality TV star toward the Republican presidential nomination and eventually the White House. 

Christie remained a friend and outsider adviser during Trump’s presidency but broke with him over the deadly Jan. 6 insurrection at the U.S. Capitol by Trump supporters bent on disrupting congressional certification of Biden’s win.

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Now, nearly 10 months removed from the presidency, Trump continues to flirt with another White House run in 2024. And Christie is one of the few other Republicans mulling a GOP nomination run who’s comfortable discussing it publicly.

"Having run already, I’m not going to run for the experience. I’ve had the experience. If I run, I run because I think I can win, and I think I can make a difference," Christie told Fox News. 

War of words between Donald Trump and Chris Christie heats up

Then President-elect Donald Trump waves to the media as Gov. Chris Christie arrives at the Trump National Golf Club Bedminster clubhouse in New Jersey on Nov. 20, 2016. (AP Photo/Carolyn Kaster, File)

Christie’s Saturday speech grabbed plenty of headlines and appeared to irritate the former president, as Trump fired back two days later.

In a statement on Monday, Trump charged that Christie "was just absolutely massacred by his statements that Republicans have to move on from the past." 

And Trump spotlighted that "Chris left New Jersey with a less than 9% approval rating – a record low, and they didn’t want to hear this from him!"

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Christie, in an interview this week with Mike Allen of Axios, returned fire.

"I’m not gonna get into a back-and forth with Donald Trump. But what I will say is this: When I ran for reelection in 2013, I got 60% of the vote. When he ran for reelection, he lost to Joe Biden," Christie said. "I’m happy to have that comparison stand up, because that’s the one that really matters."

And he emphasized that "this is not an argument that I'll walk away from."