12:05 PM PT -- After 15 minutes of speaking, Robert F. Kennedy Jr. announced he's not terminating his run -- he's simply suspending the campaign.

He thanked all his volunteers across the country and campaign staff. He then handed his support to Donald Trump.

"We changed the national conversation forever," he said.

He said polling consistently shows that by staying on the ballot in battleground states, that would hand the presidency to Democrats -- an outcome he wants to avoid.

Robert F. Kennedy Jr. is delivering a speech in Phoenix ... a day after withdrawing from the Arizona ballot. He's expected to announce he's dropping out of the race for president.

This comes among widespread speculation the independent candidate will endorse Republican nominee Donald Trump for president. Trump is also in Arizona Friday.

RFK Jr.'s speech will be "about the present historical moment and his path forward," his campaign announced this week.

Trump is scheduled to speak later today in nearby Glendale, AZ. Trump’s campaign announced yesterday he would be joined by “a special guest” at the Glendale event.

RFK Jr.'s third-party campaign has struggled to certify the required signatures to appear on various state ballots, qualifying for 23 state ballots, but facing legal challenges in others.

On Friday, the campaign requested ballot removal from Pennsylvania, according to the Associated Press.

His attempt at appearing on the debate stage in June with Republican nominee Donald Trump and President Joe Biden failed -- that fateful night eventually leading to Biden bowing out of the race and passing the torch to VP Kamala Harris, who just wrapped up a popular Democratic National Convention in Chicago this week.

RFK Jr. did challenge Trump to a head-to-head debate at the Libertarian National Convention in May, though Trump declined. On Trump's Truth Social platform he proclaimed “RFK Jr. is a Democrat ‘Plant,’ a Radical Left Liberal."

RFK Jr. caught a storm of attention after admitting he was behind an infamous NYC prank involving a dead bear cub left on a Central Park bike path in 2014. A photo from back then shows him with his finger in the dead bear's mouth.

Back in May, Kennedy confirmed that a parasitic worm had eaten part of his brain, and had died while still inside his skull, resulting in "brain fog."

RFK Jr.'s campaign maintained his run was "independent of the broken two party system and the corporate corruption" of the government. The campaign focused on issues including the environment, foreign intervention, the country's southern border and middle-class concerns.