Donald Trump and his former vice-president, Mike Pence, have held rival rallies for Republican candidates hoping to be Arizona's state governor.
Trump spoke at an event for Kari Lake, who backs his false claims about election fraud, while Pence supports her opponent, Karrin Taylor Robson.
They fell out after Trump accused Pence of failing to block President Joe Biden's election victory in 2020.
Trump claimed the election was stolen from him and wanted his vice-president to refuse to certify the election result, but Pence decided this would be illegal.
During the Capitol riot on 6 January 2021, when a mob of his supporters stormed Congress in an effort to overturn the result, Trump tweeted that Pence "didn't have the courage to do what should have been done to protect our Country".
The riot is currently being investigated by a congressional inquiry, which heard on Thursday night that Mr Trump had watched events unfold on TV at the White House, ignoring his children and aides who "begged him" to rebuke the mob.
At her rally on Friday in the central Arizona town of Prescott Valley, Ms Lake, a former TV news journalist, told supporters that "rigged elections" would no longer be accepted.
Meanwhile, Mr Pence spoke in favour of Ms Taylor Robson at a rally in Peoria, saying: "No one worked harder for the Trump-Pence ticket in 2016 or in 2020."
He did not criticise Mr Trump or refer to the election controversy during his speech.
However, he said later in a tweet that "if the Republican Party allows itself to become consumed by yesterday's grievances, we will lose".