(The Hill) — Republican strategist Scott Jennings advised former President Trump to be careful now that he has seemingly joined forces with Robert F. Kennedy Jr., arguing the independent presidential candidate is “kind of a looney tune.” 

CNN anchor Wolf Blitzer asked Jennings Friday if Kennedy’s endorsement could “end up backfiring” on the former president, considering the environmental lawyer’s controversial views on vaccines and embrace of some conspiracy theories. 

The senior CNN pundit responded that while he thinks most of Kennedy’s supporters will end up backing Trump in November, there could be negative strings attached. 

“There could be some cost on the other side of the algebra,” Jennings said. “I mean, I’m old enough to remember when RFK was a liberal, you know, conspiracy theorist. Now he’s more of a conservative conspiracy theorist, but the through line is, he’s a conspiracy theorist, and a lot of people think he’s kind of a looney tune.” 

“So, I would just caution the former president to be a little careful here,” he continued in the interview on CNN’s “The Situation Room,” highlighted by Mediaite. “Don’t make any promises, you can’t get out of because this guy, over the course of his career, has been a, you know, a little bit, so just careful.”

Kennedy initially ran for the White House as a Democrat. In October, he left the party to campaign as an independent.

After seeing his poll numbers dip from low double-digits, he announced in Arizona that he would suspend his campaign and endorse Trump. Hours later, he joined the former president at his campaign rally outside Phoenix, with Trump saying he will have a “huge influence on this campaign.”

Kennedy said he would remove his name from ballots in key swing-states to not end up being the difference-maker in the election but would still compete in most blue and red states. 

Democrats have often gone after the long-shot candidate, arguing he was a fringe contender more closely aligned with Republicans. In response to the news that Kennedy would back the GOP nominee, Vice President Harris‘s campaign did not directly mention the independent, but instead offered a new vision for the country.

“For any American out there who is tired of Donald Trump and looking for a new way forward, ours is a campaign for you,” Harris campaign Chair Jen O’Malley Dillon said in a statement. “In order to deliver for working people and those who feel left behind, we need a leader who will fight for you, not just for themselves, and bring us together, not tear us apart. Vice President Harris wants to earn your support.”

Trump’s campaign, however, heralded the decision. The team released a memo from its pollster, Tony Fabrizio, positing that the former president would gain the majority of Kennedy’s supporters in a head-to-head race against Harris.