Independent presidential candidate Robert F. Kennedy Jr. announced on Tuesday in Oakland he was picking one of his presidential campaign’s major financial backers, lawyer and philanthropist Nicole Shanahan, to join him as the vice presidential candidate on his ticket for his long shot White House bid.

Kennedy, an anti-vaccine conspiracy theorist and Kennedy family scion, said he picked Shanahan because she shares his views on health, artificial intelligence, the regulatory state, immigration and other issues. He also cited her experience as a “gifted administrator” and passion for athletics, as well as her relative youth. The 38-year-old has never held elected office.

“I’m so proud to introduce to you the next vice president of the United States: my fellow lawyer, a brilliant scientists, technologist, a fierce warrior mom: Nicole Shanahan,” Kennedy said at a campaign rally.

Shanahan gave $4 million to an outside super PAC backing Kennedy earlier this year to fund a Super Bowl ad, telling the New York Times she aided in the ad’s production. The frequent Democratic donor has worked as a lawyer in the tech industry and was previously married to Google co-founder Sergey Brin.

She now leads Bia-Echo Foundation, an organization she founded to direct money toward issues including women’s reproductive science, criminal justice reform and environmental causes.

“Nicole and I both left the Democratic Party," Kennedy said in Oakland. "Our values didn’t change. The Democratic Party did.”

Shanhan previously donated to Democratic presidential candidates in 2020, including Marianne Williamson and now-Transportation Secretary Pete Buttigieg. After Joe Biden secured the Democratic nomination that year, she donated $25,000 to one of his campaign accounts and $5,600 to another, federal campaign finance records show. The same day she donated $19,400 to the Democratic National Committee.

In 2016, she financially supported Hillary Clinton’s campaign.

Kennedy's campaign has spooked Democrats, who are fighting third-party options that could draw support from President Joe Biden and help Republican former President Donald Trump. As they head into a 2020 rematch, Biden and Trump are broadly unpopular with the U.S. public and will compete for the votes of people who aren't enthusiastic about either of them, according to polling.

National general election polls in the last month have shown Kennedy Jr. polling percentages as high as the mid-teens.

The DNC had planned a press call in the hours after his announcement to level their attacks on Kennedy “about the stakes in this election” and Kennedy’s ties to Republican donors. California Rep. Robert Garcia, Pennsylvania Lt. Gov. Austin Davis and Michigan state Sen. Mallory McMorrow are expected to be on the call.

Without the backing of a party -- he briefly ran as a Democrat before launching an independent bid -- Kennedy faces an arduous task to get on the ballot, with varying rules across the 50 states. He’s picking a running mate now because about half of the states require him to designate one before he can apply for ballot access. His campaign pledged on Tuesday they would be on the ballot in every state.

The running mate requirement is already bedeviling Kennedy's ballot access effort in Nevada, where Democratic Secretary of State Francisco Aguilar said in a March 7 letter to independent candidates that they must nominate a vice presidential candidate before collecting signatures. The letter came days after Kennedy's campaign announced he'd collected enough signatures in the state. If Aguilar's opinion survives a likely legal challenge, Kennedy will have to start again in collecting just over 10,000 signatures in the state.

"This is the epitome of corruption,” said Paul Rossi, a Kennedy campaign lawyer, in a statement Monday, accusing Aguilar of doing the bidding of the DNC.

Kennedy has secured access to the ballot in Utah. He and an allied super PAC, American Values 2024, say they’ve collected enough signatures to qualify in several other states, including swing states Arizona, Nevada and Georgia, but election officials there have not yet signed off.

In advance of an event Tuesday in Oakland, Kennedy and his aides had circulated the names of several contenders, including celebrities with no political experience. Those names include NFL quarterback Aaron Rodgers, “Dirty Jobs” star Mike Rowe and former Minnesota Gov. Jesse Ventura, who was a wrestler and actor.

“This announcement is really going to shake up the political establishment,” Kennedy said in a video he posted on social media last week.

Kennedy has built a reputation as an activist, author and lawyer who fought for environmental causes such as clean water. But he has spent decades spreading anti-vaccine disinformation and conspiracies, contradicting long-accepted scientific consensus. He has falsely claimed that COVID-19 was “ethnically targeted” to harm white and Black people, while largely sparing Ashkenazi Jews and Chinese people. Last year, he said “no vaccine is safe or effective.”

Earlier this year, Shanahan said she was “not an anti-vaxxer” but wanted more examination of the dangers of vaccines, which have been used safely by billions of humans to prevent life-threatening diseases for decades. According to the U.S. Centers for Disease Control and Prevention, four million deaths worldwide “are prevented by childhood vaccination every year.”

Kennedy is a descendant of a storied Democratic family that includes his father, Robert F. Kennedy, who was a U.S. senator, attorney general and presidential candidate, and his uncle former President John F. Kennedy.

Kennedy was a teenager when his father, known as RFK, was assassinated during his own presidential campaign in 1968. 

Some members of his family have publicly criticized the independent presidential candidate’s views. Dozens of Kennedy family members sent a message when they posed with Biden at a St. Patrick’s Day reception at the White House in a photo his sister Kerry Kennedy posted to social media.

“From one big Irish Catholic family to another, it’s great to have the Kennedys here,” Biden said to the Kennedy contingent during one event that day. At another event, the president told the family members “welcome almost home” and said “it wouldn’t be St. Patrick’s Day without you.”

Two hours before RFK Jr.’s rally on Tuesday was scheduled to begin at a performing arts venue, a handful of supporters were lined up outside. Broken-down cars, discarded bicycles, tents and all manner of household goods took up the sidewalk and a park directly outside, a visual reminder of the housing crisis that has plagued California.

Dozens of men in black suits made up a heavy security presence for a candidate who has loudly complained that he has not been granted protection from the U.S. Secret Service. RFK Jr.’s campaign has spent millions of dollars with the security company owned by Gavin de Becker, who has been a major donor to his campaign and associated super PAC.

RFK Jr. is leveraging a network of loyal supporters he's built over years, many of them drawn to his anti-vaccine activism and his message that the U.S. government is beholden to corporations.

The Democratic National Committee, meanwhile, is gearing up to take on Kennedy and other third-party options, including No Labels, a well-funded group working to recruit a centrist ticket. The effort is overseen by veteran strategist Mary Beth Cahill, whose resume includes chief of staff to the late Sen. Edward M. Kennedy of Massachusetts, another of RFK Jr.'s uncles.

Many Democrats blame Green Party candidates for Al Gore’s loss to George W. Bush in 2000 and Hillary Clinton’s loss to Trump in 2016.