New Delhi, July 20 -- PHOENIX - The Republican primary for Arizona governor, set for Tuesday, July 22, has become something more than a contest between two incumbents seeking different offices. It is a test of which faction of the party, the MAGA populism of the House Freedom Caucus or the traditional fiscal conservatism that once defined the state's brand, that can survive a general election against an incumbent Democratic governor that most strategists already consider among the most vulnerable in the country.

On one side is Andy Biggs, the former House Freedom Caucus chairman who built a national profile by refusing to certify the 2020 election results and became one of Donald Trump's most reliable allies in Congress. Biggs has Trump'...