Now, don’t get me wrong — there is some interesting variation in the second-choice vote shares that jibes with sorting candidates into “lanes.” To take one example, Sanders ranks as the preferred second choice of supporters of Sen. Elizabeth Warren, whose progressive economic message dovetails with Sanders’s. To take another, Sen. Kamala Harris ranks higher among Sen. Cory Booker supporters than she does among any other candidate’s supporters, and Booker likewise does better among Harris supporters than he does any other bloc. That supports the idea that Harris and Booker, as the race’s two most prominent African-American candidates, might appeal to similar bases.
But it’s less variation than I think most people would expect, and there are clearly large chunks of voters who are perfectly willing to vote for a candidate in a different lane. As political scientist David A. Hopkins of Boston College recently pointed out, voters simply aren’t so well informed or calculating to split candidates cleanly into such factions. What’s more, lanes haven’t accurately predicted how previous presidential nominating contests would shake out after candidates began withdrawing and support started shuffling around. Current events and the shifting media spotlight after candidates win or outperform expectations in early primary states can also shake up fields, and candidates’ own marketing efforts can often succeed at winning over voters that may not be part of their “natural constituency.” Voters may use ideology and identity as a guide, but “lanes” are hardly an ironclad theory. Frankly, primaries are unpredictable — maybe we should all just get more comfortable with that idea.