Helen Purcell served in that office for seven terms---28 years. She was respected and well-regarded until one big screw-up.
Purcell, a Republican, hurt herself by reducing the number of polling places in the county from the 200 used in the 2012 election to 60 for the 2016 primary, and then blamed voters for long lines and delays before finally taking responsibility.
But that was too late. 100,000+ people signed petitions calling for a DOJ investigation into voter suppression, Mayor Stanton made a formal request of the DOJ, which initiated one and members of the Arizona House called for her resignation. Adrian Fontes, a Democrat, capitalized on all that and beat her in the general.
Had Purcell not severely restricted the number of polling places, there would have been no controversy and she likely would have won re-election yet again.
Fontes lost re-election in 2020 by fewer than 5,000 votes and gets the last laugh, beating Republican election denier Mark Finchem for Secretary of State in the 2022 general election held last week.