Supporters of Chris Christie's 2024 Republican presidential campaign who are courting New Hampshire Democrats to cast a ballot in support of the former New Jersey governor and against former President Donald Trump in the state's upcoming lead-off primary are out of time.

Two political groups backing Christie's second White House run have been sending mailers to registered Democrats in the state that holds the first primary and second overall contest in the GOP presidential nominating calendar. And they've been running targeted digital ads.

They're wooing Democrats by highlighting that Christie is the only Republican presidential candidate "willing to take Trump on" and urging them to "make sure" the former president "never sees the inside of the Oval Office again."

But the deadline for New Hampshire voters to change their registration ahead of next year's presidential primary is Friday.

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Pro-Christie groups court New Hampshire Democrats to switch parties to vote against Trump in primary

Mailers by the Chris Christie aligned super PAC Tell It Like It Is which were sent to Democrats in New Hampshire urge them to change their voter registration by Oct. 6 so they can vote in the upcoming Republican presidential primary for Christie and against former President Donald Trump (Tell It Like It Is super PAC)

The mailers by the Christie aligned super PAC Tell It Like It Is and the digital spots by the until now under the radar nonprofit policy organization American Leadership Today explain that Democrats can "switch parties by October 6 and VOTE in the Republican Primary. It's easy to switch your party affiliation back after!"

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The narrator in the digital ad warns that "in New Hampshire on a cold January night, democracy will be on the ballot."

American Leadership Today has also been sending text messages and direct mail to Democrats in New Hampshire with the same message.

Chris Christie stops by the Red Arrow Diner in Manchester, New Hampshire

Republican presidential candidate and former New Jersey Gov. Chris Christie speaks with a voter at the Red Arrow Diner, on June 22, 2023 in Manchester, New Hampshire (Fox News (Paul Steinhauser))

Seven years ago, Christie placed all his chips in his first bid for president on New Hampshire. However, his campaign crashed and burned after a disappointing sixth-place finish in New Hampshire, far behind Trump, who crushed the competition in the primary, boosting him towards the Republican nomination and eventually the White House. 

Christie became the first among the other GOP 2016 contenders to endorse Trump and for years was a top outside adviser to the then-president and chaired 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 — who is considered one of the best communicators in the GOP and was known during his tenure as Garden State governor for the kind of in-your-face politics that Trump has also mastered — has 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 as he's juggling an historic four criminal indictments, including two for attempting to overturn the 2020 election results.

Donald Trump is interviewed by Fox News Digital in Concord, N.H.

Former President Donald Trump is interviewed by Fox News Digital in Concord, New Hampshire, on June 27, 2023.  (Fox News - Paul Steinhauser)

But with Trump not taking the stage in the initial GOP presidential nomination debates, Christie has pledged to "confront" Trump elsewhere on the campaign trail to make sure that the former president is not the Republican Party's 2024 standard-bearer.

As he runs for the White House a second time, Christie is once again concentrating his efforts in New Hampshire. He's seen his poll numbers rise in Granite State over the summer, but he and the rest of the field of contenders remain far behind Trump in the latest surveys.

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This week's mailers and digital ads are the latest evidence that Christie is banking on support from independents and Democrats who loathe Trump and are deeply concerned about the prospects of the former president returning to the White House.

A spokesperson for American Leadership Today said in a statement that the group's "goal is spreading awareness about available choices through a multi-faceted campaign and expanding voter participation in the Granite State’s proud First In The Nation primary process."

Chris Christie allies gambit for Democrats in New Hampshire

Former New Jersey Gov. Chris Christie, a 2016 Republican presidential candidate who's making another White House run, headlines a town hall in Gilford, New Hampshire on Oct. 5, 2023 (Fox News - Deirdre Heavey)

Christie, during a stop in New Hampshire last month at a town hall in North Hampton, offered that he was "uncomfortable with the idea of asking people to change their party. Because I think that’s something that’s very personal for them to decide."

But he urged eligible voters "should go out and vote and vote for the person that they think will make a difference."

Asked about the mailers and digital ads, which were first spotted by WMUR-TV political director Adam Sexton, Trump campaign spokesman Steven Cheung took aim at Christie.

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"Of course Chris Christie is begging Democrats to support him. Chris Christie is a stone cold loser who spends every day on the cable news casting couch auditioning for a contributor contract whenever his joke of a campaign ends up in flames," Cheung charged in a statement.

Donald Trump calls the latest federal indicment against him 'bulls---'

Republican presidential candidate former President Donald Trump speaks at a campaign event on Tuesday Aug. 8, 2023, at Windham High School in Windham, New Hampshire (AP Photo/Robert F. Bukaty) (AP)

Will the gambit by Christie's allies work?

With a likely uncompetitive Democratic presidential primary in New Hampshire, there's the belief that the state's large pool of independent, or undeclared, voters - as well as some Democrats - will cast ballots in the GOP contest. 

"What we've seen in the polling is that Trump's support has remained solid among Republican primary voters. So if you can't have Trump's number decline, you have to find new voters. And those new voters could be undeclared or independents, but they could also be Democrats who decide to switch to undeclared and potentially take a ballot in the Republican presidential primary," New Hampshire Institute of Politics executive director Neil Levesque told Fox News.

But he noted that "it's a difficult thing to convince somebody to change their registration, which entails physically going to their town hall to make that change, in an effort to vote against a candidate."

"Who knows — it could make a difference in a tight election. But in the past we haven't seen that it's really been a factor," Levesque said.

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