Donald Trump and his ex-wingman Mike Pence, who went from White House partners to bitter rivals, will hold dueling rallies Friday in Arizona, where a state primary could serve as an early battleground in their potential 2024 showdown.
The convergence of campaign events comes a day after a Congress hearing investigating the US Capitol insurrection, in which a White House security official said members of Pence's Secret Service detail feared they would die as rioters stormed the building.
Trump, who like Pence is considering running for president in 2024, has savaged his former vice president for what he describes as a failure to block the certification of the 2020 election results and send the process back to the US states.
Such a plan had been cooked up by Trump aides who supported his discredited theory that the election was stolen.
During the January 6, 2021 insurrection Trump tweeted an attack on Pence, saying he "didn't have the courage to do what should have been done to protect our Country."
Administration officials testified at Thursday's hearing that the social media post poured fuel on the fire and turned rioters against the vice president.
In extraordinary revelations at the hearing, a White House national security official who testified under anonymity said "members of the VP detail at this time were starting to fear for their own lives."
"There were calls to say goodbye to family members," he added. "For whatever reason it was on the ground, the VP detail thought this was about to get very ugly."
On Thursday Trump again attacked the long-established US election certification process, taking to his social media platform Truth Social to accuse Pence of serving as "a 'human conveyor belt'" who could do nothing to block the result.
"It was all a 'Big Lie.' Should have sent back to states!" he posted.
Trump is holding a "Save America Rally" in the central Arizona town of Prescott Valley, where he will campaign for Kari Lake, a far-right gubernatorial candidate who supports his false claim that the election was stolen.
"Big rally in Arizona Friday evening. See you there!" he wrote.
Pence will make stops in Phoenix and southern Arizona for governor hopeful Karrin Taylor Robson, a more traditional Republican than Lake.
"Looking forward to campaigning with the next governor of Arizona, @Karrin4Arizona!" Pence tweeted Friday.
With his rivalry with Trump intensifying, Pence has positioned himself as a principled, religious conservative. But while he is considering his own presidential bid, he has declined to attack Trump.
For now he says his focus is the November 2022 midterm elections.
"Then in 2023 we'll look around," Pence told the National Review last year. "We'll go where we're called."