I see 5 pickups from these states that President Trump won with >10% of the vote:
Indiana (Joe Donnelly)
Missouri (Claire McCaskill)
Montana (Joe Tester)
North Dakota (Heidi Heitkamp)
West Virginia (Joe Manchin)
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We could also take some of these that President Trump won with <10% of the vote:
Florida (Bill Nelson)
Michigan (Debbie Stebenow)
Ohio (Sherrod Brown)
Pennsylvania (Bob Casey)
Wisconsin (Tammy Baldwin)
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The only potentially vulnerable Republican I see is:
Nevada (Dean Heller)
(...because Nevada voters chose Hillary)
Although Clinton won Nevada, in 2016, she didn’t win a majority, here. She got 47.9%, and Trump got 45.5%. Johnson got 3.3%. In the U.S. Senate race, the Democrat, Catherine Cortez Mastro, got 47.1%, and the Republican, Joe Heck, got 44.7%. “None of these candidates” (a choice that is only available in NV) got 3.8%, and Tom Jones, of the Independent American Party (the NV affiliate of the Constitution Party) got 1.5%. I think that a majority of the people, who voted for “None of these candidates,” are conservatives.