Arizona's 4th Congressional District is considered a heavily Republican district.
CD4 covers much of the western edge of Arizona. It's largely rural areas, also including Kingman, Bullhead City, Prescott, Yuma, and even wraps around northeast of the Valley into Pinal County.
Gosar has been representing the area that is now Congressional District 4 since 2011.
Paul Gosar
Republican Gosar was elected as a U.S. Representative in 2010.
Gosar studied dentistry and had a dentistry practice in Flagstaff for 25 years. He was a leader in professional dentistry organizations.
In 2015, Gosar was the only member of Congress to skip Pope Francis's address to a joint meeting of Congress, saying the Pope should not talk about climate change, and should focus on other messages like pro-life policy and condemning ISIS.
"The Second Amendment is one of the most important rights guaranteed by the Bill of Rights," Gosar's website says.
In September, Gosar's own brothers and sisters were featured in a campaign ad endorsing Brill.
David Brill
Brill is a political newcomer. As a medical doctor, he headed up Primary Care at the Veterans Administration.
The Democratic candidate has been endorsed by various Democratic candidates and leaders in Arizona.
"I will fight for simple, affordable, accessible health care for every American," reads Brill's campaign website. "No one should lose, or be unable to afford, health care because of job loss or life transition."
Haryaksha Gregor Knauer
Knauer is the Green Party candidate in CD4, winning the primary unopposed with 295 votes. He ran for Arizona House of Representatives District 1 in 2016.
MORE: 12 News voter guide
