Mary Rose Wilcox has resigned from the Maricopa County Board of Supervisors so she can run for Congress.
Board Chairman Denny Barney called Friday for applications for the open supervisor's position.
The remaining board members will appoint an interim replacement.
Wilcox announced in March that she filed the paperwork to run for Congress representing Arizona's 7th District.
The seat is currently held by U.S. Rep. Ed Pastor, who announced last month that he'll retire at the end of his current term.
Wilcox will run against former state Rep. Ruben Gallego.
Pastor's Phoenix-area district is heavily Democratic and whoever wins the August primary is expected to easily win November's general election.
Steve Gallardo resigned from the Arizona House earlier this year to also run for the 7th District, but he recently dropped out of the race, saying he plans to instead run for the County Supervisor spot that Wilcox is leaving. [Related: Steve Gallardo bows out of congressional run]
Wilcox, 64, currently is serving her fifth, four-year term on the county Board of Supervisors representing the fifth district, which spans from downtown Phoenix to the western and southern borders of Maricopa County. It includes south Phoenix, Buckeye, the Gila River Indian Community and Gila Bend.
She previously served on the Phoenix City Council for nine years.
Wilcox and her husband own El Portal, a local Mexican restaurant.
Copyright 2014 CBS 5 (KPHO Broadcasting Corporation). All rights reserved. The Associated Press contributed to this report.