President Trump, with a Truth Social post early this morning, is laying into the independent candidate for president, Robert F. Kennedy Jr., mocking his intelligence while insisting that he “wants to” accept Mr. Kennedy’s challenge to debate, but first the Kennedy scion would need “to get his bad poll numbers up.”

Mr. Trump wrote that Mr. Kennedy draws eight percent “at best” in polls. He then called him “a Radical Left Lunatic whose crazy Climate Change views make the Democrat’s Green New Scam look Conservative.” As he did in a Truth post on Saturday, he urged Americans, “Don’t waste your precious vote.” 

Mr. Trump said he wants to debate both of his opponents and concluded that Mr. Kennedy “probably hurts Sleepy Crooked Joe more than ‘US.’” This mirrored findings in a survey released Tuesday by the Hill and Emerson University.

In that poll, Mr. Biden trails Mr. Trump in Arizona, Georgia, Wisconsin, Pennsylvania, North Carolina, Michigan, Nevada — and Mr. Kennedy’s inclusion expands that lead. Democrats, including many in the Kennedy family, call this proof that RFK Jr. hurts Mr. Biden and ought to drop his bid.

Speaking at Brooklyn on Wednesday, Mr. Kennedy called Mr. Biden the “real spoiler.” He cited a 50-state Zogby survey he’d commissioned that showed him beating Mr. Biden in the Electoral College by 196 votes and topping Mr. Trump by two. Mr. Trump topped Mr. Biden by 50. 

Mr. Kennedy described a spoiler as a candidate not “able to win themselves” and prevents “someone else from winning who otherwise would.” He challenged Mr. Biden to sign a “No-Spoiler Pledge” committing to co-fund a national survey with the loser agreeing to drop out of the race against Mr. Trump.

On Sunday at Holbrook, Long Island, Mr. Kennedy said, “I have yet to talk to anybody — outside of my family — who says, ‘We’re voting for President Biden because he is energetic and because he’s got the cognitive capacity to outsmart everybody in the world, and he’s going to give us a new vision for America.’” 

Setting his sights on both opponents, Mr. Kennedy touted a Fox poll that showed him leading on favorability. In his Truth post today, Mr. Trump dismissed the claim, stating that Mr. Kennedy “says he does well against Crooked Joe and me, one on one.” Mr. Trump exclaimed: “WRONG, he gets trounced.”

After his Truth post on Saturday highlighting Mr. Kennedy’s positions and calling him “not a serious person” whose “views on Vaccines are FAKE, as is everything else about his Candidacy,” it was Mr. Trump calling on Mr. Biden to debate. 

Noting the incumbent had “committed” to faceoffs last week, the 45th president said, “Let’s set it up right now. I’m ready to go anywhere that you are.” In an X post on Saturday, Mr. Kennedy responded to Mr. Trump’s broadsides by needling him with the same skewer. “President Trump,” he said, “who has proven himself the most adept debater in modern American political history, should not be panicked to meet me on that stage.”

Mr. Kennedy offered a “preview” of his debate arguments. Mr. Trump, he wrote, had “betrayed the hopes of his most sincere followers” on a range of issues. He cited support for Mr. Biden’s aid package for Ukraine, running up the national debt, appeasing “Big Pharma,” and filling “his administration with swamp creatures.”

“Instead of lobbing poisonous bombs from the safety of his bunker,” Mr. Kennedy wrote, “let’s hear President Trump defend his record to me mano-a-mano by respectful, congenial debate.” On Tuesday he asked on X, “Why do YOU think President Trump won’t debate me?” 

Mr. Biden refused to debate Mr. Kennedy during the Democratic primaries before the challenger’s “declaration of independence.” Mr. Trump also refused to participate in GOP primary faceoffs. Mr. Kennedy’s challenge now casts his opponents as both afraid to meet him on the hustings alone.

“Mr. Kennedy believes,” his campaign told me in May, “the American people want and deserve debates.” By throwing down the gauntlet to Messrs. Trump and Biden, RFK Jr. is making a case that the title he seeks isn’t “spoiler” but president of America.