Top Trump advisers, who say they are cautiously optimistic over how Donald Trump will perform today, believe their success or failure in these final hours ultimately comes down to one issue: turnout.

“We feel like we’re in a position now where, if the people who we think are going to turn out for President Trump turn out, then he ought to win. So it’s a matter of achieving that. It’s close. It’s really close,” a senior Trump adviser told CNN.

“I hate to sound so ridiculous. ‘Oh, it’s turnout,’ but that’s really what this comes down to and the only thing we’re focused on right now.”

“Whereas before turnout for him was maybe surprising, especially in 2016, and a lot of people were silent about their vote and that didn’t always register in the data, it’s unclear if we’ll see that type of difference this time around,” a person close to Trump told CNN.