Arizona will vote Feb. 28, and that state — along with Michigan, which votes the same day — is expected to be the most intensely competitive upcoming contest. The candidates are looking to solidify a solid front-runner status. Mitt Romney’s lead has faltered, bending under Rick Santorum’s three wins on Tuesday. Newt Gingrich and Santorum have both surged and waned multiple times in the polls.

Brewer called the primary “a little nasty but exciting.”

"It's been up, it's been down, and I think that we are anxiously awaiting to have them all come out here for our debate Feb. 22, and then I think we’ll really have the proof of who is going to win Arizona,” she said.

Brewer is a polarizing figure and the influence of her endorsement is debatable. South Carolina Gov. Nikki Haley endorsed Romney ahead of her state’s primary, and another supporter, former Minnesota Gov. Tim Pawlenty, campaigned for Romney in his state, but Romney won neither contest. South Carolina went to Gingrich and Minnesota to Santorum.