WASHINGTON, July 21 (Reuters) – Voters will go to the polls ⁠on ⁠Tuesday in Arizona to choose Republican and ⁠Democratic nominees for the U.S. Congress and governor, with races that will set the tone ​for November’s midterm elections in a state known for its competitive elections and politically independent streak.   Registered Republicans outnumber registered Democrats in Arizona, but ‌the large number of independents makes for ‌a state that is considered closely divided.  Both parties have had combative primary competitions in one of the most closely watched races in ⁠the country: Arizona’s ⁠1st congressional district. With Republican Representative David Schweikert leaving the House of Representatives at year’s ​end as he attempts to become Arizona’s next governor, Democrats have targeted this open Phoenix metropolitan district seat as a top priority in their quest to win  majority control of the House from Republicans. Republicans currently hold 218 House seats to Democrats’ 212 seats, not counting one independent who ​caucuses with Republicans and four vacancies. Democrats need a net gain of four seats to win majority control of ⁠the …