Ciscomani and Gosar face Democratic challengers as voters weigh immigration, housing shortages and fundraising gaps in two November races.
Immigration and housing policies are at the center of Arizona's 6th and 9th congressional district races, contests that could determine control of Congress in November.
In the 6th District, Incumbent Rep. Juan Ciscomani faces JoAnna Mendoza, with fundraising showing Mendoza leading with about $6.5 million while Ciscomani holds a cash advantage of nearly $1 million.
U.S. Rep. Paul Gosar seeks a ninth term against Democrat Danielle Sterbinsky in the 9th District, with Gosar leading fundraising with more than $575,000 compared to Sterbinsky's more than $354,000.
President Donald Trump endorsed both incumbents, touting Ciscomani's immigration agenda and Gosar's support for administration priorities, while candidates differ on the FAST Housing Act and Social Security benefits.
Polls for the Arizona primary open Tuesday, July 21, from 6 a.m. to 7 p.m. MST, setting the stage for the Nov. 3 general election where congressional control remains at stake.