Mr. Pence grew close with Mr. Kemp during the pandemic and 2020 campaign, and now he is lining up against Mr. Trump’s handpicked candidate, former Senator David Perdue. But more than that, Mr. Pence is seeking to claim a share of credit in what’s expected to be the starkest repudiation yet of Mr. Trump’s attempt to consolidate power, with Mr. Kemp widely expected to prevail.

It is an emphatic break between the onetime running mates, who have not spoken for nearly a year but have also not publicly waged a proxy war until now. Mr. Pence, his aides say, knows full well what going down to Georgia represents and the symbolism alone will stand without him targeting Mr. Trump or even Mr. Perdue in his remarks.

In a statement ahead of Mr. Pence’s visit to Georgia, Mr. Trump belittled his vice president through a spokesman.

“Mike Pence was set to lose a governor’s race in 2016 before he was plucked up and his political career was salvaged,” said Taylor Budowich, the spokesman. “Now, desperate to chase his lost relevance, Pence is parachuting into races, hoping someone is paying attention. The reality is, President Trump is already 82-3 with his endorsements, and there’s nothing stopping him from saving America in 2022 and beyond.”