Independents empirically vote against incumbents
Cook 20 [Charlie, political analyst, one of the nation's leading authorities on U.S. elections and political trends; “As Is Their Habit, Independents Seem to Be Breaking Against the Incumbent”; 6/26; The Cook Political Report; https://www.cookpolitical.com/analysis/national/national-politics/their-habit-independents-seem-be-breaking-against-incumbent] /sb
When Trump won 46 percent of the vote nationwide, 2 points behind Hillary Clinton’s 48 percent, he did it in part by winning the 31 percent of the vote that exit polls showed was cast by independents, 46 to 42 percent. Staying within 2 points of Clinton nationally kept him within range to squeak out his two-tenths-of-a-point win in Michigan and seven-tenths-of-a-point margins in Pennsylvania and Wisconsin.
What many don’t appreciate is that voters who consider themselves independent have a tendency to vote for change in every presidential election. 2016 marked the fifth consecutive election in which independents have voted in favor of the party not holding the White House, by an average of 4 percentage points. In 2000, when Al Gore was trying to hold onto the White House for Democrats after Bill Clinton’s eight-year presidency, independents voted for George W. Bush from the opposition Republican Party by 2 points, 48 to 46 percent. Four years later, independents again sided with the opposition party, but just by a point, going for John Kerry over Bush by 49 to 48 percent. In 2012, Mitt Romney won independents by 5 points, 50 to 45 percent. So independents’ move against Hillary Clinton should not have been surprising.