We don’t tend to talk much about undecided voters in political analysis. Sometimes, you can gloss over them altogether by referring to a candidate’s polling lead, such as “Dems plus-5.”
But undecided voters can decide elections; in 2016 they played a key role in swinging toward Mr. Trump in the critical battleground states. This year, the battle for control of the House is more than close enough for a similar swing to flip the House either way.
Over the last three weeks, we’ve interviewed more than 1,000 undecided voters in Upshot/Siena polls of competitive congressional races. CONT.
Nate Cohn, New York Times