Robert F. Kennedy Jr. announced Friday he is suspending his long-shot campaign for president and instead supporting former President Donald Trump.

He did so at an event in Phoenix, Arizona, during which he encouraged voters in red or blue states to vote for him but said he would remove himself from the ballot in battleground states where he could act as a "spoiler."

"I want everyone to know that I am not terminating my campaign," he said. "I am simply suspending it and not ending it."

Soon after, Kennedy joined Trump on stage during the former president's Glendale, Arizona, rally.

Trump said he would appoint and create an independent commission to investigate assassination attempts and release all remaining documents about the 1963 assassination of President John F. Kennedy.

He went on to explain what drove him to enter the race, to leave the Democratic Party and "now to throw my support to President Trump."

Just before he took the stage, his campaign filed a court document in Pennsylvania that said Kennedy would endorse Trump.

Trump, who was in Nevada campaigning as Kennedy spoke, quickly celebrated his support. Trump will be in Arizona later Friday to hold a rally in Glendale, where he teased he would be joined by a "special guest."

"We just had a very nice endorsement from RFK Jr., Bobby," Trump said in Las Vegas. "That's big. He's a great guy, respected by everybody."

Meanwhile, the Democratic National Committee responded to Kennedy's announcement with a statement of "good riddance."

"The more voters learned about RFK Jr. the less they liked him," said DNC senior adviser Mary Beth Cahill. "Donald Trump isn't earning an endorsement that's going to help build support, he's inheriting the baggage of a failed fringe candidate."

In his Phoenix speech, a teary-eyed Kennedy made clear he was basing his choice around his yearslong passion for one key issue: chronic illness in children.

With his path to the White House all but shut, he reasoned, he would align with the one remaining candidate who expressed interest in taking up the cause.

"If President Trump is elected and honors his word, the vast burden of chronic disease that now demoralizes and bankrupts the country will disappear," Kennedy said.

"This is a spiritual journey for me. I reached my decision through deep prayer, through hardnosed logic, and I asked myself, what choices must I make to maximize my chance to save America's children and restore national health?" he continued.

"I felt that if I refused this opportunity, I would not be able to look myself in the mirror knowing that I could have saved lives of countless children and reversed this country's chronic disease epidemic."

Some in Kennedy's inner circle had concerns about endorsing Trump, whose team ramped up its courtship of Kennedy only when polls last month began showing the former President trailing in the race.

But at least one person with knowledge of the conversations between Trump and Kennedy in recent weeks told ABC News Trump has shown "genuine care to attack" the issue of chronic disease.

"There was a deep connection, and I think a realization" about the importance of the issue, the person said.

Kennedy gave his remarks in a ballroom at a downtown Phoenix hotel, with dozens of staff and top supporters having flown in with little notice to attend the hastily prepared event.

Kennedy began his White House run in April 2023 as a Democrat to challenge President Joe Biden, but months later dropped the bid and the party that his family has symbolized for decades to chart a new course as an independent. He named Nicole Shanahan, a Silicon Valley lawyer, to be his running mate.

Kennedy's vaccine skepticism stance and controversial remarks about COVID-19 had alienated him among Democrats, and he frequently sparred with the Democratic National Committee about the primary process, which he decried as unfair.

Members of his own family, too, were critical of his views and of his presidential run. Fifteen Kennedy family members made a statement by endorsing Biden at a campaign stop in Philadelphia when he was still in the race.

Five of his siblings released a joint statement on Friday stating they believed in Vice President Kamala Harris and her running mate, Minnesota Gov. Tim Walz.

"We want an America filled with hope and bound together by a shared vision of a brighter future, a future defined by individual freedom, economic promise and national pride. We believe in Harris and Walz," said Kathleen Kennedy Townsend, Courtney Kennedy, Kerry Kennedy, Chris Kennedy and Rory Kennedy.

"Our brother Bobby's decision to endorse Trump today is a betrayal of the values that our father and our family hold most dear," they continued. "It is a sad ending to a sad story."