PHOENIX – Two congresswomen will face off in the sole Arizona Senate debate Monday evening, capping a contest that could determine which party controls the U.S. Senate.

The race pits two triathletes and congresswomen against each other who have won multiple elections in swing districts.

Martha McSally is a former fighter pilot who represented a Tucson district that voted for Hillary Clinton and was a Trump critic during 2016. She’s now embraced the president and hoping he visits to unite Republicans against the Democrat, Kyrsten Sinema.

Kyrsten Sinema represents a district based in the Phoenix suburb of Tempe and is a former Green Party activist who transformed herself into a centrist Democrat. She has one of the most conservative voting records among Democrats in congress and presents herself as a nonpartisan problem-solver.

Sinema and her allies have relentlessly focused on health care and criticized McSally for voting for the GOP bill that would have replaced President Obama’s health care law with a system that had weaker protections for people with pre-existing conditions.

McSally and her allies have attacked Sinema as a phony and a closet liberal, airing footage of her at protests against the Afghanistan and Iraq wars at the start of the century.

McSally has said repeatedly she needs Republicans to unify behind her candidacy. The GOP has won every statewide election in Arizona since 2006 but Democrats and some Republicans think Sinema could peel off enough Republican moderates to win this year.

Democrats also hope last spring’s massive teacher walkouts help power their voters in the senate race and elsewhere.