Oro Valley's loss may just be Pima County's gain.

Mark Napier, who in March finished fifth out of six candidates in an impromptu bid to join the Oro Valley Town Council, now finds himself as the strongest challenger in years for longtime Pima County Sheriff Clarence Dupnik.

The 50-year-old former Tucson Police Department captain, 50, blew away a crowded field to win the GOP nomination for sheriff, getting more than 43 percent of the 59,199 votes counted as of Wednesday. That is just barely fewer than the candidates who finished third, fourth and fifth—combined.

"If somebody said we would pull almost 28 points in a five-way race I’d say I don’t think so," said Napier, who credits a strong ground game orchestrated by his support staff, as well as a commitment to keep his campaign positive. "And I think the message stays the same, it’s one of positive. It’s simply time for a new sheriff. I think most people in Pima County realize that. They want a visible, engaged, dynamic sheriff, and we've missed that."

Dupnik, a Democrat seeking an eighth term, is rumored to be planning to step down sometime during the next four-year period if re-elected. Sticking to his avoidance of negativity, Napier wouldn't speak to that allegation, instead directing the person it reflects to do so.

"Sheriff Dupnik needs to speak to that; he needs to convince voters that they’re choosing him for a four-year term," Napier said.

The general election is Nov. 6, and until then, Napier said he will continue to burn the candle at three ends, so to speak. In addition to campaigning, Napier is associate director of operation for the University of Arizona's Parking and Transportation Services, and he also runs the online criminal justice program for Boston University.

"I typically work from 6 a.m. to 10 p.m.," he said. "But I've got to balance it. I'll take some vacation here and there."