FLAGSTAFF, Ariz. (AP) — Three candidates are competing to become the Republican nominee in a vast congressional district that takes in Arizona's high country, low desert and tribal land.

The 1st Congressional District was drawn to be competitive, but it has leaned Democrat since the new outlines first were used in 2012. Retired Air Force pilot Wendy Rogers, Arizona state Sen. Steve Smith, and attorney and farmer Tiffany Shedd all want to be the one to try to flip it to the GOP. Zhani Doko is a Libertarian write-in candidate.

The winner of Tuesday's Republican primary will face Democratic incumbent Rep. Tom O'Halleran in the November general election. O'Halleran, who has served one term, is unopposed in the primary and has the cash to be formidable.

At 55,000-square miles (142450-square kilometers), the district is bigger than half of the U.S. states.

Though vast, it does not touch the U.S.-Mexico border. Nevertheless, border security tops each of the Republican candidates' priorities — in line with President Donald Trump's agenda. The candidates also pledge to defend gun rights, limit the reach of the federal government, and reduce what they say are regulatory burdens on energy and economic development.

Shedd, 50, believes she's best for the job because she was raised in the district where she and her family grow cotton and wheat on their farm in Eloy. The economic drivers in rural Arizona — tourism, the forest, agriculture and water — aren't always understood by politicians, she said. Small towns struggle with the inability to match federal funds, inadequate water supplies and decent internet service, she said.

"We're not seeing the growth out here," she said. "While it's gotten better under President Trump, we need someone who actually has a background in those things not only to advocate for rural Arizona but to re-educate policymakers."

Rogers cites her experience in the military and as a business owner. She travels the district in a single-engine Cessna 182, saying it helps her reach the district's voters. She speaks with the intensity of someone in battle when describing a recent tour where she met residents of Duncan, railroad workers in Winslow worried about their pensions, veterans concerned about health care and Navajo grandmothers on their reservation.

"I am laser-focused on taking this district back from the Democrats," said Rogers, 64, who lost her bid for the GOP nomination in the district in 2016. "O'Halleran already is afraid of me."

Smith, 42, says he's the only candidate with a proven record, having served in the state Legislature since 2011. He touts bills he championed to raise private funding for a border fence, to eliminate a sales tax on coal that feeds a power plant on the Navajo Nation, defund sanctuary cities, and one to allow farmers to maintain underground water credits when not growing any crops. He says he's the candidate most closely aligned with Trump.

"I think the voters want to know, 'what have you done,' not 'what have you said,'" Smith said. "There's a big difference between talking and doing."

A key voting block will be Native Americans, who make up a quarter of the district's population.

Smith said he and Arizona Gov. Doug Ducey traveled to the capital of the Navajo Nation to sign bills that would benefit tribes and has presented his legislative work to the White Mountain Apache Tribal Council. Rogers said she's had lengthy discussions with Navajo officials, and bonds with Native veterans and grandmothers because of her military service and being a grandmother herself. Shedd said her husband and children are enrolled members of the Muscogee (Creek) Nation of Oklahoma, so she understands shared desires of tribal sovereignty and independence.

All three say O'Halleran, who served in the Arizona Legislature as a Republican from 2001 to 2009, has been ineffective as a congressman. He ran for Congress as a Democrat.

O'Halleran, 72, has introduced more than a dozen bills in Congress, including one clarifying the boundaries of the Gila River Indian Community that has passed the House.

He recently completed a 17-day tour of the district and says he's served his constituents well, pointing to his votes as a moderate Democrat. O'Halleran said he does what's best for the district's residents — regardless of political ideology — and has more name recognition than any of the GOP candidates.

"They're going to have to overcome that and, hopefully, they'll do it in a way that's respectful," he said.

O'Halleran will be at a significant financial advantage after the primary election, with more than $1.5 million cash in hand as of Aug. 8, according to campaign finance reports. Smith is leading the Republican field with $155,000, followed by Rogers with $70,000 and Shedd with $50,000.