A Schweikert loss would leave Republicans in control of only three of Arizona's nine congressional districts.
The former emergency room physician wants to expand access to Medicare and add more legal protections for those with pre-existing conditions.
Democrats see the 6th District as winnable because of a long-running ethics investigation into five-term GOP incumbent Rep. David Schweikert.
A multi-year ethics investigation into Rep. David Schweikert of Arizona concluded this week, after Schweikert admitted to 11 violations and agreed to pay a $50,000 fine.
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