Former President Donald Trump and President Biden are running neck-and-neck in a new 2024 presidential election poll, but the data suggests an independent bid by Robert F. Kennedy, Jr. could upend the race in Biden's favor.

According to a Marist poll released Tuesday, 49% of registered voters said they would support Biden, 46% Trump and 5% remained undecided — all without Kennedy in the race.

Those numbers shifted dramatically for Trump and Biden with Kennedy running as an independent candidate, but appeared to hurt Trump's chances for reclaiming the White House more than Biden's odds of winning a second term.

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2024 presidential candidates

From left: Former President Donald Trump, Robert F. Kennedy, Jr. and President Biden. (Getty Images)

The poll showed Kennedy winning 16% support among voters, Trump 37% and Biden 44%. Just 3% were undecided.

The biggest shift with a Kennedy candidacy came from independent voters, showing a massive drop in support for Trump (49% to 34%) and Biden (43% to 33%), according to the poll. Kennedy received support from 29% of independents.

Republican support for Trump also dropped significantly from 91% to 81%, with Kennedy receiving support from 11% of GOP voters.

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Independent presidential candidate Robert F. Kennedy Jr.

Robert F. Kennedy, Jr. visits supporters at the Adrienne Arsht Center for the Performing Arts in Miami on Thursday. (Al Diaz/Miami Herald/Tribune News Service via Getty Images)

Biden also saw a drop in support from Democrats with Kennedy in the race, from 91% to 86%, but not as a significant a loss as Trump's among Republicans. Kennedy received support from 9% of Democrats.

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Kennedy announced on Oct. 9 he would be running as an independent after attempting a run against Biden and fellow Democrat Marianne Williamson for the party's presidential nomination. He ultimately made the decision after the Democratic National Committee maintained its backing of Biden and refused to hold any primary debates.

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