Shadow campaigns: 7 Democrat candidates who could step in if President Biden drops out of 2024 race

President Biden’s widely panned debate performance has sparked a firestorm of speculation on whether Democrats will switch horses midstream and select a new presidential nominee from a generally accepted list of candidates.

VICE PRESIDENT KAMALA HARRIS

Harris, 59, would seemingly be the most logical fit, offering the smoothest transition given her position as vice president, and some calls for her to step in have already been issued.

"After deep reflection over these past few days, I strongly believe that our best path forward is Kamala Harris," Tim Ryan, the former Democrat congressman and presidential candidate, wrote in Newsweek on Monday.

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Potential Biden replacements are Kamala Harris, Gavin Newsom, Gretchen Whitmer and Pete Buttigieg. (Getty Images)

Many experts have raised concerns about the vice president’s approval rating as her poll numbers have plummeted since taking office. Earlier this year, polling showed Harris was viewed negatively by a combined 53% of registered voters and positively by a combined 28% of voters.

CALIFORNIA GOV. GAVIN NEWSOM

If Democrats were to make a move away from Biden, potentially at the Democratic National Convention in August, the most talked about successor in recent months has been California Gov. Gavin Newsom.

Newsom, 56, has long been accused of running a "shadow campaign" for president over the past year as he has engaged in high-profile events, including trips to China and Israel, and a highly publicized Fox News debate with Florida GOP Gov. Ron DeSantis.

Newsom, who is headed to New Hampshire this week to headline a Democrat campaign event just days after Biden’s debate performance, has consistently denied any plans to step in for Biden.

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California Gov. Gavin Newsom speaks to reporters after the presidential debate between President Biden and former President Trump in Atlanta on June 27, 2024. (AP Photo/John Bazemore)

"I will never turn my back on President Biden," Newsom said on Thursday after the debate. "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."

MICHIGAN GOV. GRETCHEN WHITMER

Whitmer, who won re-election in 2022 by a double-digit margin, has previously hinted at interest in a presidential run and has reportedly vaulted to the top of the list in terms of donor preference in recent weeks.

Online supporters have been pushing a "Draft Gretch" message, and Politico reported after the debate that Whitmer spoke with Democratic Party leadership and disavowed that movement while also warning that Michigan is no longer in play for Biden.

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Michigan Gov. Gretchen Whitmer (AP Photo/Alex Brandon/File)

Whitmer later dismissed that reporting and reaffirmed her support for Biden.

"I am proud to support Joe Biden as our nominee and I am behind him 100 percent in the fight to defeat Donald Trump," Whitmer said in a statement on Monday. "Not only do I believe Joe can win Michigan, I know he can because he’s got the receipts."

TRANSPORTATION SECRETARY PETE BUTTIGIEG

Buttigieg burst onto the national scene in 2020 when he ran for president after serving eight years as the mayor of South Bend, Indiana, inspiring the nickname "Mayor Pete."

Speculation has continued to grow that he would be willing to step in if Biden were to drop out of the race, but lukewarm polling numbers and transportation issues across the United States could potentially harm a Buttigieg candidacy. 

"No, that’s easy," Buttigieg said Friday when asked if he would support an effort to find a new nominee.

PENNSYLVANIA GOV. JOSH SHAPIRO

Shapiro, 51, is governor of perhaps the most critical swing state in the 2024 presidential election, and polling last year showed him with a 57% job approval rating against 23% who disapprove.

Shapiro took office in January 2023 after beating his Republican opponent by nearly 15 points.

"Popular governor of a critical swing state," Allegheny County Republican Party Chair Sam DeMarco posted on X after the presidential debate. "If you don’t think he’s getting calls tonight, you’re deluding yourself."

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Former President Trump (Felipe Ramales for Fox News Digital/File)

ILLINOIS GOV. J.B. PRITZKER

Pritzker, who was re-elected in 2022 by about 12 points, delivered a victory speech that many believed sounded like a politician who wants to run for president one day.

Pritzker said earlier this year that Democrats are "throwing away their votes" if they support anyone besides Biden.

Pritzker, 57, a billionaire equity investor and philanthropist, has been one of the most outspoken Democrats against former President Trump.

KENTUCKY GOV. ANDY BESHEAR

Beshear, from one of the most popular political families in Kentucky, won re-election in the deep-red state last year as a Democrat and has recently been rumored to be a top candidate to step in and replace Biden.

Beshear told reporters Monday that even though Biden’s recent debate performance was "rough," he has no intention of sliding into presidential contention unless Biden bows out of the race.

"He is the candidate, and as long as he is, I’m supporting him," Beshear said.

Trump has gone ahead of Biden in their 2024 election rematch in the aftermath of last week's presidential debate, according to a new national poll conducted in the wake of Biden's extremely rough performance.

The former president stands at 41% support and Biden at 38% among registered voters nationwide in a USA Today/Suffolk University survey conducted Friday through Sunday and released on Tuesday.

The Democrat incumbent in the White House and his Republican predecessor were tied at 37% in the previous USA Today/Suffolk University poll, which was conducted in May.

On Tuesday, the first elected Democrat in Congress called on Biden to step down.

Rep. Lloyd Doggett of Texas said in a statement that Biden should "make the painful and difficult decision to withdraw."

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"My decision to make these strong reservations public is not done lightly nor does it in any way diminish my respect for all that President Biden has achieved," Doggett said. "Recognizing that, unlike Trump, President Biden’s first commitment has always been to our country, not himself, I am hopeful that he will make the painful and difficult decision to withdraw. I respectfully call on him to do so."

Biden campaign spokesperson Michael Tyler said there have been no internal conversations "whatsoever" about Biden stepping aside, though he, too, acknowledged the president had a "bad night" onstage.

Fox News Digital’s Jamie Joseph, Paul Steinhauser, Kyle Morris, Greg Wehner and the Associated Press contributed to this report.