With just five days left until mid-term elections, Republicans and Democrats alike going to be making lots phone calls and knocking on lots of doors, trying to reach out and talk to undecided voters — or as they’re called in polling circles, “persuadables.” That little semantic shift that reveals how desirable these voters are and what lengths a campaign will go to in order to get them. 

But who are these persuadables? And what exactly do they need to be persuaded?

Record numbers of Americans voted early this year. Michael McDonald, a voting expert and professor at George Mason University, analyzes what we know about those early votes, and what they say about what will happen tomorrow.