Lesko had been endorsed by Freedom Caucus leaders Rep. Mark Meadows (R-NC) and Rep. Jim Jordan (R-OH), as well as Arizona Caucus member Rep. Andy Biggs (R-AZ) and the Caucus's political arm, the House Freedom Fund. She was known for her fiscally conservative record during her tenure in the Arizona state legislature, but was criticized by opponents for directing funds between three different campaign committees, with Montenegro describing it as "money laundering".

Montenegro, an immigration hardliner, had received the backing of Franks and Sen. Ted Cruz (R-TX), as well as figures from the nationalist wing of the party such as Sheriff Joe Arpaio, Rep. Steve King (R-IA), and former Rep. J.D. Hayworth (R-AZ). Despite being the early frontrunner, his campaign faltered after a scandal emerged surrounding his inappropriate text conversations with a female aide, who went on to send him nude photos.