Three sources inform NBC News that Pinal County Sheriff Mark Lamb will announce next week his candidacy to run for Arizona’s U.S. Senate seat.

Lamb’s entry could open up a crucial Republican primary match-up against Kari Lake, the defeated candidate for governor and close ally to Donald Trump.

The GOP nominee would be facing a three-way matchup with Democrat Ruben Galego and incumbent Independent Kyrsten Silena. She has yet to officially announce her reelection campaign.

This race is seen as a prime target for Republicans to flip a seat in the state’s Senate, which has lost three consecutively.

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Pinal County is a sprawling 5,000-mile area that runs between Tucson and Phoenix. Lamb, who has been vocal in his criticism of President Joe Biden’s handling of the southern border has told a U.S. House Committee in March that his deputies had seized increasing amounts of fentanyl as well as encountered more human-trafficking cartel movements.

As he contemplated his future run, Lamb was a regular at Arizona GOP’s major campaign events. Trump made a comment to the crowd last October at an Arizona rally that Lamb, a lawman with a goatee who wears a cowboy cap and has a beard, is from “central casting.” He also published “American Sheriff” in 2020.

The potential Senate candidacy of Lake helped to ice the field through the winter. Despite the rumblings of others contemplating their bids, no Arizona Republican has crossed Lake. She continues to fight for her gubernatorial defeat in the Arizona courts.

Lake lost last November by just over 17,000 votes against Katie Hobbs, a Democrat. However, in her GOP primary she defeated her chief opponent Karrin Taylor Robson by just 5%. Taylor Robson’s campaign had outspent Lake by approximately a 5-to-1 margin.

Taylor Robson, Blake Masters and Taylor Robson are still considering their own Senate runs.

Masters was defeated by Mark Kelly, Democrat, by 5% in November.