A statement from Kemp accompanied the announcement.
"Today, I’m proud to endorse Mike Collins to be the next congressman for Georgia’s 10th Congressional District. As a conservative small businessman, Mike knows firsthand how the disastrous policies of the Biden administration are hurting hardworking Georgians and communities all across our state. Mike is strongly pro-life, pro-2nd Amendment, and will fight hard to put Georgians first in Congress. I will be casting my ballot for Mike Collins in the June 21st GOP runoff, and I ask fellow Republicans across the district to join me in sending a trusted conservative to Washington!"
Collins, the son of a former congressman, is running against former DeKalb County CEO Vernon Jones, backed by former President Donald Trump. Early voting for the runoff began June 13. The winner's Democratic opponent in the November general election will also be decided in a runoff Tuesday.
Collins edged Jones in the eight-candidate primary on May 24. Neither reached the 50% threshold to avoid a runoff.
Jones initially campaigned for Georgia's governor but made way for Trump endorsed candidate David Perdue. Jones drew attention from Republicans after the longtime Democrat changed party affiliations and became a staunch supporter of former President Trump.
The Collins campaign has been critical of Jones' time as DeKalb CEO. Tuesday, Jones filed a complaint with the Morgan County Sheriff's Office over a tweet sent by Collins' campaign that includes two photographs: one of a rape whistle with RealVernonJones.com printed on it and the other of a pink handgun.
"Although some use a rape whistle for protection against sexual assault, a 9mm is the more preferred form of protection #TheMoreYouKnow," the tweet reads.
"He’s encouraging violence against me, my family, my supporters," Jones told FOX 5 Atlanta. "These are the same false attacks that liberals used against President Trump, Justice Kavanaugh, and Justice Clarence Thomas."
The Associated Press contributed to this report.