The first major gathering of Turning Point USA since the murder of its influential founder Charlie Kirk was supposed to bring America's right-wing activists together to celebrate his life.

Instead, it is laying bare the divisions of a fractious conservative coalition, increasingly worried about its electoral prospects and about President Donald Trump's fraying popularity.

Key figures in the Make America Great Again movement took to the stage in Phoenix to tear into each other, blasting opponents for cozying up to fascists or accusing them of besmirching the memory of a man who acted as a unifying force.

Influential podcaster Ben Shapiro came straight out of the gate, attacking former Fox News host Tucker Carlson for an uncritical interview with self-described white nationalist Nick Fuentes.

"The conservative movement is... in danger from charlatans who claim to speak in the name of principle, but actually traffic in conspiracism and dishonesty," he said.

Shapiro said Carlson should never have given oxygen to Fuentes, whose views are described as antisemitic, misogynistic and racist.

Kirk had "despised" Fuentes, Shapiro added. "He knew that Nick Fuentes is an evil troll and that building him up is an act of moral imbecility, and that is precisely what Tucker Carlson did."

Carlson shot back, mocking Shapiro for suggesting censorship, which he claimed was anathema to the Turning Point founder.

"Deplatforming and denouncing people at a Charlie Kirk event. I'm like, what? It's hilarious," he told the audience a few hours later.

The brewing MAGA civil war is over who will take the reins when Trump – who cannot run for the White House again – steps back.

No one has formally declared their candidacy for the 2028 Republican presidential nomination, but a number of names are being bandied around as pretenders to the throne.

They include Fuentes and firebrand congresswoman Marjorie Taylor Greene, who last month broke with Trump, saying his second term agenda was a betrayal of his voters.

Vice President JD Vance, who is due to speak at the gathering on Sunday, has gotten a significant boost when Kirk's widow Erika endorsed him for a 2028 White House run.

The Vance endorsement from Turning Point's new CEO is why Shapiro is annoyed, hinted Carlson, whose newsletter on Friday gloated "Sorry, Ben Shapiro, JD is America First." (AFP)