Former Arizona state senator wins primary for vacant House seat
"This was a team effort and I am so thankful, I am so blessed," Lesko told an enthusiastic crowd, including former Arizona governor Jan Brewer, who stood by her side. "Wow, this is sweet."
Former state senator Steve Montenegro and former state representative Phil Lovas, who were also front-runners, conceded on Tuesday night.
The seat was vacated by Republican Trent Franks in December after he said two female staffers complained he had discussed with them his efforts to find a surrogate mother to bear his child. He denied any wrongdoing.
Lesko will face emergency room physician Dr Hiral Tipirneni in the general election on April 24.
Tipirneni defeated Brianna Westbrook, a transgender woman who has advocated for anti-discrimination protection for gays, in the Democratic primary on Tuesday, the Arizona Secretary of State website showed.
Analysts said the winner of the Republican primary would be heavily favored to win the general election.
Lesko has expressed support for Republican President Donald Trump, taken anti-abortion stances and backed tough immigration measures, tighter border security and gun rights.
"I look forward to welcoming Debbie to Congress after she wins the general election on April 24, so she can join in our efforts to pursue more conservative reforms that will help Arizona and American families get ahead," House Speaker Paul Ryan said in a statement.
Lesko became embroiled in controversy over moving $50,000 garnered from her state Senate race to a political action committee that backs her congressional campaign. She said the move was legal.