It’s full steam ahead for Biden-Harris 2024, despite polls that show many voters want to see a different nominee. But what if, for any reason, President Joe Biden was unable to run?

Here are some potential and current candidates who could find themselves at the top of national polls — and who might be quietly positioning themselves for the opportunity — should Democrats need a new nominee next year:

Vice President Kamala Harris

As vice president, not only is Harris a heartbeat away from the presidency, but she has high name ID and support from many voters in her party. A Monmouth University poll earlier this year found 13% of Democrats said they’d like Harris to be their nominee if Biden didn’t run, higher than any other potential candidate. Like Biden, Harris saw her approval dip below her disapproval during the summer of 2021 and it hasn’t recovered, according to her national polling average on FiveThirtyEight.

California Gov. Gavin Newsom

As Florida Gov. Ron DeSantis has held up his state as a conservative model for the rest of the country, Newsom has done the same on the left with California. Newsom has argued it’s Democrats and not Republicans who are the party of freedom, pointing to book bans and abortion restrictions, and his campaign even ran billboards promoting California’s abortion laws in Republican-run states. Newsom told the San Francisco Chronicle editorial board last year he has “sub-zero” interest in running for president, but his recent media appearances suggest he wants to be in the national spotlight.

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Sen. Bernie Sanders

Sanders, I-Vt., came in second in two consecutive Democratic primaries, and the Monmouth University poll earlier this year found 6% of Democratic voters wanted him to try a third time, behind only Harris. Before Biden announced his reelection campaign, Sanders indicated he was open to another run, but in April, Sanders told The Associated Press he would “do everything I can to see the president is reelected.” At 81 years old, Sanders is older even than the 80-year-old Biden, which could be a challenge for voters concerned about the president’s age.

Transportation Secretary Pete Buttigieg

After rocketing from former mayor of South Bend, Indiana, to 2020 Iowa caucus winner, Buttigieg has made a name for himself as Transportation Secretary in Biden’s administration. The Monmouth University poll found Buttigieg tied with Sanders with 6% support. Buttigieg is 41.

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Robert F. Kennedy Jr.

The son of the former U.S. attorney general and nephew of John F. Kennedy, RFK Jr. announced his campaign for the Democratic nomination in April. Kennedy has made a name for himself promoting conspiracy theories about vaccines, and even before the COVID-19 pandemic, members of his family criticized his views. In an editorial published in Politico in May 2019, Kathleen Kennedy Townsend, Joseph P. Kennedy II, and Maeve Kennedy McKean said RFK Jr. “has helped to spread dangerous misinformation over social media and is complicit in sowing distrust of the science behind vaccines.” A USA Today/Suffolk University poll released Sunday found Kennedy has 15% support among Democrats.

Marianne Williamson

A bestselling author whose books include “A Return to Love” and “The Healing of America,” Williamson ran for president in 2020 and made it onto the debate stage before dropping out before the primaries began. She announced her 2024 campaign in March and is polling at 6%, according to the USA Today/Suffolk University poll.