Marianne Williamson becomes first Democrat to challenge Biden for 2024

Self-help author Marianne Williamson told donors on Sunday that she will run for president as a Democrat in 2024, mounting what is likely to be a primary challenge to President Joe Biden from his left flank.

Williamson, who also sought the Democratic presidential nomination in 2020 but failed to make any primary, will likely challenge Biden from the left, should he ultimately run for reelection as expected. She is unlikely to get any institutional support, including from powerful progressives in Washington, as the Democratic Party appears to be coalescing around the president.

In the donor email, obtained by ABC News, Williamson suggested she will offer a clashing vision to Biden's, arguing the country is fundamentally heading in the wrong direction while implicitly responding to concerns over her electability.

Williamson wrote that she will formally launch her bid during a speech this coming Saturday.

"My qualification is not that I'm experienced at running that system, but that I'm best qualified to help transform it. Washington is filled with good political car mechanics, but the problem is that we are on the wrong road," she wrote.

"[S]ince the election of 2016 it's odd for anyone to think they can know who can win the presidency. And I'm not putting myself through this again just to add to the conversation," Williamson wrote. "I'm running for president to help bring an aberrational chapter of our history to a close, and to help bring forth a new beginning."

Williamson first garnered a following writing several bestselling self-help books and working with various public health-related charities.

In 2020, she ran in a field of more than two dozen Democratic presidential candidates on a largely pacifist message. She also became known for using similar language from her self-help experience in her campaign, including calling out then-President Donald Trump and saying she would "harness love" to defeat the "fear" he had deployed to entice voters.

Williamson also embraced a slate of progressive policies like so-called "Medicare for All" and a $15 minimum wage.

Separately, she has had to combat controversy around vaccines, particularly in in the wake of COVID-19, after calling vaccine mandates "Orwellian" in 2019. She has since said there is a legitimate debate to be had around such mandates but that she is inoculated against COVID-19.

Biden, for his part, has not definitively said he will run for president, though he is widely expected to launch a campaign by the summer.

"[M]y intention is -- from-- has -- intention has been from the beginning to run. But there's too many other things we have to finish in the near term before I start a campaign," he told ABC News anchor David Muir in an interview at the White House last week.

Biden is the oldest sitting president and would be 86 at the end of a second term.

"It's legitimate for people to raise issues about my age. It's totally legitimate to do that. And the only thing I can say is -- watch me," Biden told Muir.

ABC News' Brittany Shepherd contributed to this report.