California Gov. Gavin Newsom is headed to New Hampshire to headline a Democrat campaign event just days after the Biden-Trump presidential debate, fueling more speculation that he may be preparing to step in if Biden backs out of the 2024 race. 

The July 8 event, called the "Blue Summer Campaign Kick-Off," is being spearheaded by the New Hampshire House and Senate Democrats.

New Hampshire is a key swing state in the general election and Newsom, who is a top surrogate for President Biden’s 2024 re-election campaign, will also be campaigning for the president and other Democrats up and down the ticket during his stop in the Granite State, according to sources familiar with his plans.

"We look forward to welcoming Governor Newsom to New Hampshire to campaign on behalf of President Joe Biden and Vice President Kamala Harris as we work to once again defeat Donald Trump," longtime New Hampshire Democratic Party chair Ray Buckley said in a statement.

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left/right split photos: Gov. Newsom and President Biden

Newsom and Biden (Getty Images)

Arguing that "Trump has grown increasingly unhinged in his campaign for power," Buckley emphasized that "it’s never been more important to mobilize Democrats across the state to defeat him and re-elect our President, Joe Biden, who has consistently fought for and delivered for New Hampshire."

Newsom assured reporters in the spin room after Thursday night's presidential debate that he remained firmly behind Biden — who has faced significant criticism even from members of his own party for a lackluster performance.

"I will never turn my back on President Biden," Newsom said on Thursday in a comment that appeared designed to dispel rumors that he's running a shadow campaign. "I don't know a Democrat in my party that would do so. And especially after tonight, we have his back."

Newsom added: "I spent a lot of time with him. I know Joe Biden. I know what he's accomplished in the last three and a half years. I know what he's capable of. And I have no trepidations."

FETTERMAN HITS NEWSOM FOR NOT HAVING ‘GUTS’ TO ADMIT HE'S RUNNING SHADOW CAMPAIGN AGAINST BIDEN

Left: President Biden giving thums up; Right; Gov. Gavin Newsom

Left: President Biden. Right: California Gov. Gavin Newsom. (Getty Images)

Leading up to the debate, rumors continued to swirl that Newsom, a possible future contender for his party's presidential nomination, had been tapped as a Biden surrogate leading up to the November presidential election.

When pressed if he was "ready to take on Donald Trump" – a question that hinted at the rumors that he could be a potential replacement for Biden – Newsom again denied any ulterior motives.

Last year, Biden told a group of world leaders that Newsom "could have the job I’m looking for" if he wanted it, a joking reference that nevertheless alluded to Biden's diminished approval rating and the rising discontent within his party.

"I want to talk about Governor Newsom. I want to thank him. He’s been one hell of a governor, man," Biden said during a welcome reception for Asia-Pacific Economic Cooperation (APEC) leaders in San Francisco. "Matter of fact, he could be anything he wants. He could have the job I’m looking for."

Sen. John Fetterman, D-Pa., also accused Newsom of running a shadow campaign for the presidency last year, roughly around the same time that Newsom engaged in a debate with Republican Florida Gov. Ron DeSantis that was hosted by Fox News' Sean Hannity. 

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Trump and Biden in left-right photo split

Democrats and liberal media pundits are dismissing polls showing Donald Trump's gains among Black voters. (Getty Images)

"Let me say something that might be uncomfortable," Fetterman said at a Democratic Party dinner in Iowa. "Right now there are two additional Democrats running for Pennsylvania, excuse me, running for president right now. One, one is a congressman from Minnesota. The other one is the governor of California. They're both running for president, but only one had the guts to announce it."

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Biden has given no indication that he plans to drop out of the race. 

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

Fox News Digital's Paul Steinhauser, Stepheny Price, Aubrie Spady and Cameron Cawthorne contributed to this report.