Environmental lawyer and high-profile vaccine critic Robert F. Kennedy, Jr. on Wednesday formally launched a 2024 Democratic presidential primary challenge against President Biden.

Kennedy, the 69-year-old son of the late senator, attorney general and presidential candidate Robert F. Kennedy and the nephew of the late President John F. Kennedy, declared his candidacy for the White House at a campaign launch event at a hotel in downtown Boston.

"I've come here today to announce my candidacy for Democratic nomination for President of the United States," Kennedy said after taking the stage. "My mission over the next 18 months of this campaign, and throughout my presidency, will be to end the corrupt merger of state and corporate power that is threatening now to impose a new kind of corporate feudalism on our country."

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Describing himself as a truth teller, Kennedy charged that state and corporate powers have "poisoned our children and our people with chemicals and pharmaceutical drugs, strip mine our assets to hollow out the middle class and keep us in a constant state of war."

Pointing to his famous family political dynasty, Kennedy said "my whole family including myself have long personal relationships with President Biden." He added that many of his family members disagree with him on a range of issues, but he still loves them. "Is it too much to hope that we could have the same thing for our country?" Kennedy asked.

He warned that "we have a polarization in our country today that is so toxic, so dangerous, than at any time since the Civil War."

Kennedy pledged that his goal will be to end that division by encouraging people to talk about common values rather than the issues that divide. "I'm going to do that by telling the truth to the American people," he said.

He also took aim at the media, charging that "we know the media lies to us. Everybody knows that."

The announcement comes nearly two weeks after Kennedy political representatives filed paperwork with the Federal Elections Commission to begin setting up the campaign.

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Kennedy becomes the second nationally known Democrat to launch a long-shot primary challenge against the president. Marianne Williamson, the best-selling author and spiritual adviser, last month launched her second straight campaign for Democratic presidential nomination, and has been campaigning in New Hampshire, South Carolina and other early voting primary states.

Marianne Williamson at the New Hampshire State Senate

Democratic presidential candidate Marianne Williamson is greeted by New Hampshire state Senate president Jeb Bradley at the Statehouse in Concord, N.H., on March 9, 2023. (New Hampshire State Senate)

Biden, whose approval ratings among all Americans remain in negative territory, has repeatedly said that he intends to seek a second term in the White House, but he has yet to make any formal announcements. Biden told reporters this past weekend that an announcement would come "relatively soon."

As Kennedy jumps into the race, a new national poll from USA TODAY/Suffolk University suggested that 14% of voters who backed Biden in 2020 would support Kennedy in 2024.

According to the survey, which was conducted Sunday through Tuesday, two-thirds of Biden’s 2020 supporters said they’d back the president again for the Democratic nomination, with Kennedy at 14%, Williamson at 5% and 13% undecided.

Kennedy has faced criticism from fellow Democrats for his activism against the COVID-19 vaccine, and his emerging role in recent years as a crusader for individual liberties has made him an increasingly popular figure on the political right.

While Kennedy insists that he's not opposed to vaccines and that his sole interest is to make them safer, his Children's Health Defense non-profit has been accused of spreading doubts about the safety of vaccines.

Kennedy's notoriety on the issue is a main reason why most of the major figures in his famous political family were absent from his campaign launch.

In his address, Kennedy railed against the nationwide lockdowns implemented in 2020 as the coronavirus — the worst pandemic in a century — swept the globe.

And he blamed then-President Donald Trump for allowing the shutdowns on his watch, saying "the worst thing that he did to this country was the lockdown."

Robert F. Kennedy Jr. speaks at an event where he announced his run for president on Wednesday, April 19, 2023, at the Boston Park Plaza Hotel, in Boston. (AP Photo/Josh Reynolds) (AP )

In his speech, Kennedy also vowed if elected president to "end the chronic disease epidemic" in the country by attacking the root causes. "This is crippling to the middle class of this country," he said.

Kennedy's address was lengthy, as he spoke for nearly two hours. At one point, saying he was only about halfway done with his speech, Kennedy joked, "This is what happens when you censor somebody for 18 years."

He also joked about not being the ideal, typical or careful presidential candidate. "I had a rambunctious youth, and it lasted until my early 60s," Kennedy said, and he kidded about all the "skeletons in my closet."

"In normal circumstances I would not do this. But these are not normal circumstances. I’m watching my country being stolen from me," Kennedy said. "I don’t want the Democratic Party to be the party of fear and pharma and censorship… We need to stand up against corporations and stand against war."

The ballroom at the Park Plaza Hotel in Boston, where Kennedy made his announcement, was jam-packed. Fox News witnessed a standing room-only crowd, with an overflow room filled as well. The Kennedy campaign said that "thousands of people" were in attendance.

Brian Dignan, a registered independent from New York, told Fox News: "I’m absolutely supporting him. I have one word of why I am voting for this man — and that’s 'courage.'"

"Bobby Kennedy has it. He has courage. And he’s demonstrated that courage throughout his career," Dignan added. "And the fact that he’s running at all in light of the history of his whole family is tremendously courageous. And I think the whole Kenney family has demonstrated that courage throughout the years." 

Pamela San Clemente, a central Massachusetts resident who described herself as an independent conservative, said, "I’m here because I so admire all his work with medical freedom, with freedom in general. With Constitutional issues… this push towards globalism that’s anti-sovereignty."

"I just feel like he’s a person who’s highlighting all those issues and I just want to learn more about his candidacy because I so admire what he’s done with issues that are important to me," she added.

Robert F. Kennedy Jr. in New Hampshire

Environmental lawyer and anti-vaccine advocate Robert F. Kennedy, Jr. speaks at Saint Anselm College's New Hampshire Institute of Politics in Goffstown, N.H., on March 3, 2023. (Fox News )

Kennedy sparked speculation about a potential White House run early last month by visiting New Hampshire, which for a century has held the first primary in the presidential nomination race. He was joined on his trip to the state by his wife, actress Cheryl Hines, best known for portraying the wife of Larry David on the popular HBO comedy series "Curb Your Enthusiasm."

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Kennedy earlier this year took aim at Biden and the Democratic National Committee over the decision to move the New Hampshire presidential primary out of its position as the first in the nation primary. New Hampshire will now vote second in the DNC’s calendar, along with Nevada, three days after South Carolina, under the DNC’s new schedule.

President Biden speaks at the Democratic National Committee Winter Meeting in Philadelphia on Feb. 3, 2023. (AP Photo/Patrick Semansky)

Ahead of the DNC's final approval of the schedule in early February, Kennedy wrote an open letter to the committee, urging members to keep New Hampshire in the first spot because of the state's long history advocating for civil rights and election transparency. 

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The DNC changed the nominating calendar in an effort to reflect more diversity in the Democratic Party, but Kennedy said that New Hampshire already showcases the diversity in America. As a general election battleground state, he said, New Hampshire's "four electoral votes could decide the 2024 election." 

Kennedy is being helped in his campaign by former Democratic Rep. Dennis Kucinich of Ohio, who made unsuccessful bids from the left for the party's presidential nomination in 2004 and 2008. Kucinich introduced Kennedy at Wednesday's campaign launch.

Pundits view Kennedy and Williamson as long-shots for the 2024 nomination against Biden. But with the president likely to stay off the ballot in New Hampshire to avoid an unsanctioned primary, Kennedy and Williamson will grab plenty of national media attention and could create a bit of mischief in the Democratic nomination race.

Fox News' Aubrie Spady contributed to this report