CONCORD, N.H. — Former New Jersey Gov. Chris Christie is ramping up his pledge to confront former President Donald Trump on the Republican presidential campaign trail, though he doesn't want to share his plans just yet.

"Get ready. That’s all I’m going to tell you," Christie told Fox News on Thursday after he filed to place his name on the presidential primary ballot in New Hampshire, which holds the second contest in the 2024 GOP nominating calendar.

"Because if I give [Trump] and the Secret Service a tip as to where I’m going to be, it will be a lot harder for me to get to him. Remember, he’s the only guy walking around with Secret Service protection. So, that makes all of this a little more complicated. But I also was in law enforcement, so hang with me," Christie said.

For months, Christie, who's making his second White House run, has vowed to take down Trump on the debate stage.

CHRISTIE PLACES ALL HIS 2024 CHIPS ON THIS KEY PRIMARY STATE

Chris Christie files to place name on NH primary ballot

Former New Jersey Gov. Chris Christie, a 2024 Republican presidential candidate, files to place his name on New Hampshire's first-in-the-nation GOP presidential primary ballot in Concord, N.H., on Thursday. (Fox News/Paul Steinhauser )

Christie, who like Trump is a master of in-your-face politics, repeatedly touted that he's got the debate chops to target Trump. The former president remains the commanding front-runner for the Republican nomination as he makes his third straight White House run, even while juggling an historic four criminal indictments, including two for his alleged attempt to overturn his 2020 election loss to President Biden.

But with Trump skipping the first two GOP presidential debates and saying he won't take the stage at next month's third debate, Christie pledged early last month that he'd find another way to make sure that the former president is not the Republican Party's 2024 nominee.

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"We’ve got 100-plus days until the primary. Donald Trump and I will come face-to-face, whether it’s on a debate stage or whether it’s when he’s walking out of a building somewhere," Christie said.

Christie placed all his chips in his campaign for president eight years ago in the Granite State. However, his campaign crashed and burned after a disappointing and distant sixth-place finish in New Hampshire, far behind Trump. Trump crushed the competition in the primary, boosting him toward the nomination and, eventually, the White House. 

Former President Donald Trump picks up the pace on his visits to the first caucus state of Iowa

Former President Donald Trump speaks during a rally in Dubuque, Iowa, on Sept. 20, 2023. (AP Photo/Charlie Neibergall)

Christie became the first among the other GOP 2016 contenders to endorse Trump and for years was a top outside adviser to the president, chairing Trump’s high-profile commission on opioids. However, the two had a falling out after Trump’s unsuccessful attempts to overturn his 2020 election loss to President Biden. In the past two and a half years, Christie has become one of the harshest Trump critics in the Republican Party.

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Christie kept up his verbal attacks on Trump as he took questions from reporters. 

"He’s completely full of cr--, and he makes it up as he goes along," Christie charged.

Christie also argued that the former president is "a soulless human being. He cares about no one but himself. And any New Hampshire voter who thinks he gives a d--- about you, your life, your family, you’re kidding yourself. He doesn’t. So, if you think this race has been interesting up until now, I haven’t got my tank full of gas yet. He’s in for it."

And Christie emphasized that "guys from New Jersey are used to dealing with obnoxious blowhards from New York our whole life, so we have no problem dealing with them in a presidential race."

Trump campaign spokesman Steven Cheung, responding to Christie's broadsides, told Fox News, "What a sad, pathetic parasite. He should really drop this fake tough guy act because everybody knows he's a b----."

Christie has been the most vocal Trump critic in the still relatively large field of Republican presidential contenders. The former governor, considered one of the most effective communicators in the GOP, and the rest of his rivals remain far behind Trump.

Christie also took aim at some of his other rivals, in particular Florida Gov. Ron DeSantis and former South Carolina Gov. Nikki Haley, charging them with what he called the "pathetic act of trying to be like him [Trump] but not be like him."

But he saved most of his venom for multimillionaire biotech entrepreneur and first-time candidate Vivek Ramaswamy, who is Trump's biggest supporter in the 2024 field.

Biotech entrepreneur Vivek Ramaswamy, a Republican presidential candidate, files to place his name on the New Hampshire GOP presidential primary ballot at the Statehouse in Concord, N.H., on Wednesday.

Biotech entrepreneur Vivek Ramaswamy, a Republican presidential candidate, files to place his name on the New Hampshire GOP presidential primary ballot at the Statehouse in Concord, N.H., on Wednesday. (Fox News/Paul Steinhauser)

Ramaswamy, who came under repeated attack from Christie, Haley, former Vice President Mike Pence and Sen. Tim Scott of South Carolina at the first two debates, said he may skip next month's debate in Miami.

"I’m considering my options," he told Fox News on Wednesday after filing for the New Hampshire primary.

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Asked by Fox News about Ramaswamy's comments, Christie said, "I don’t think he liked that treatment up there. I don’t think he was used to getting pushed back on. He’s used to just shooting his mouth off and have nobody interrupt and nobody tell him he’s wrong. ... If he doesn’t want to show up, I don’t think anybody will miss him."

Christie also slammed Ramaswamy for his rival's suggestion Thursday that the U.S. build a wall not only on the nation's southern border with Mexico but on the northern border with Canada.

After Republican Gov. Chris Sununu of New Hampshire announced a new task force to help make the state's border with Canada more secure, Ramaswamy took to social media to write, "It’s not "Build-the-Wall" anymore. It’s Build *Both* Walls. I visited the Northern & Southern Borders this month. This isn’t a technical challenge, the country that put a man on the moon can fix this. It’s a question of political will."

Christie said it was "another dumb idea" from Ramaswamy and called his rival a "joker."

"If he really wants to be considered a serious candidate in this race with these dumb ideas he's putting forward, how about you guys start pressing him on it," Christie told reporters.

Ramaswamy, responding, told Fox News, "Wake up from your slumber, Chris. This is how a bipartisan establishment created our border crisis in the first place. The number of illegal crossings at our northern border this year surpasses the last 10 years combined. Once we seal the southern border, the northern border is the next frontier, and I refuse to play from behind."

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Ramaswamy campaign spokesperson Tricia McLaughlin told Fox News, "I will avoid making jokes about beaches or bridges, but the gentleman from New Jersey sure talks a big game for someone who can't even qualify for the debate stage."

Christie has yet to reach all the polling and donor thresholds the Republican National Committee is mandating the presidential candidates meet to qualify for the third debate.

But a confident Christie told Fox News, "I will qualify, and I will be there."

Get the latest updates from the 2024 campaign trail, exclusive interviews and more at our Fox News Digital election hub.