One thing that bedevils current polling on the 2024 presidential race are basic questions about just who will show up and what the electorate will look like. That’s always central to polling and it becomes much more central when the race is tight. (If it’s a 45-55 race the precise composition of the electorate becomes less important.) But take the new Ipsos/ABC News poll out today. The headlines that are running focus on the number for Adults – which Trump +2. Go to Registered Voters and it’s Biden +2. Go to Likely Voters and it’s Biden +4.
Needless to say, that 6 point difference is quite significant. It becomes even more significant if you buy the argument that this will be a low turnout election relative to recent cycles. (And for what it’s worth, I’m more skeptical about that than most people.)
For generations tighter voter screens virtually always favored Republicans, who were more consistent voters. That’s changed markedly in recent years, and is mor less explained by the changing demographic basis of the two parties, especially in terms of educational attainment. But even over the longtime this is a big delta between the population at large versus who is going to show up, at least in terms of what Ipsos is predicting.
The final point is that while pollsters have fairly good ways of determining likelihood to vote it’s still not an exact science. So the assumptions pollsters bring to work matters a lot too.