“Right when I saw Ann Kirkpatrick win, I thought ‘That’s over,’” he said in a phone interview.
Ms. Marquez Peterson and Ms. Kirkpatrick are competing for the seat being vacated by Martha McSally, in an area that has flipped back and forth from red to blue in recent years. Former Representative Gabrielle Giffords, a Democrat, represented the region until she was wounded in a mass shooting in Tucson in 2011. In 2014, her replacement, Ron Barber, a Democrat, lost his re-election to Ms. McSally by just 167 votes. Hillary Clinton narrowly won the district in 2016, a shift for a region that has consistently supported Republicans for president.
Ms. Marquez Peterson’s prospects may now largely depend on turnout from the far-right wing factions of her party, which may be more of a tough sell for a candidate who has presented as relatively moderate compared to firebrand Republicans running elsewhere. She has said she wants to run a local campaign and is not seeking an endorsement from President Trump.
At a public library in the Tucson suburbs on a recent evening, local Republican leaders and activists applauded the self-identified “American nationalist” guest speaker, who advocated revamping parts of the Constitution and railed against the idea that America is a diverse nation.
After the program, several attendees said they wished for a more conservative or populist candidate. “She knows nothing about chain migration, she’s unprepared,” Jennifer Rawson, 71, said dismissively of Ms. Marquez Peterson. But President Trump, she said, “He’s like me.”
The Republican grass roots want a representative who is “more the people’s choice,” not someone they see as an establishment pick, said Todd Clodfelter, a Republican running for re-election as a representative from Tucson to the Arizona House.
For their part, Democrats are capitalizing on national anti-Trump sentiment.
At a recent lunch at a Chinese buffet backed up into the bone-dry Santa Cruz River bed, Ms. Kirkpatrick introduced young volunteers who had quit their jobs as software engineers in Palo Alto, Calif., to come volunteer for Arizona Democrats.