Sen. John Fetterman, D-Pa., took a shot at California Gov. Gavin Newsom over the weekend over what many have referred to as a "shadow" presidential campaign against President Biden.

"Let me say something that might be uncomfortable," Fetterman said at a Democratic Party dinner in Iowa over the weekend. "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."

Fetterman continued, "I got to tell you, let me say I got an opinion. If you are a Democrat that wants to criticize and go after Joe Biden, our president, just go ahead and write a check for Trump."

The Pennsylvania Democrat was referencing a recent announcement from Democratic Rep. Dean Phillips that he will be running a primary challenge to Biden while Newsom has faced accusations in recent months of vying for the job without officially announcing.

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Newsom and Fetterman

L- Sen Fetterman R - Gov Newsom (Getty Images)

"This trip here, he's trying to build a base," GOP Congressman Doug LaMalfa told Fox News Digital last month in response to some high profile trips Newsom has taken, including to China, as speculation grows that President Biden may not run for a second term. "He's running the back channels until Biden takes himself out and the party says, 'Man we're going to get killed on this.'"

Fetterman's swipe at Newsom comes around the same time a New York Times-Siena College poll showed that Biden trails former President Trump in the key swing states of Nevada, Georgia, Arizona, Michigan and Pennsylvania.

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Rep. Dean Phillips of Minnesota campaigns in New Hampshire

Democratic Rep. Dean Phillips of Minnesota, who's primary challenging President Biden, takes questions from reporters during a stop at the New Hampshire Institute of Politics, on Oct. 31, 2023 in Manchester, N.H. (Fox News - Paul Steinhauser)

A Monmouth University poll released earlier this month showed that 76% of voters agreed Biden, 80, was "too old" to serve another term, compared to just 48% who said the same about Trump, 77. 

Newsom has denied he's running for president multiple times, and when asked, he told NewsNation's Chris Cuomo in September that he's "not worthy of that conversation" and that Biden "deserves it."

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California Gov. Gavin Newsom (John Nacion/WireImage)

The offices of Newsom and Fetterman did not immediately respond to a request for comment from Fox News Digital.