But on Wednesday, Ann Romney told ABC News no decision had yet been made — although one was coming "soon."

"There was a lot of talk. We're not quite there yet. And we're going to be there soon," the GOP candidate's wife said.

The poll also showed encouraging news for Mitt Romney: voter enthusiasm among Democrats was waning while Republicans were showing increased interest in turning out. Nearly half of Republicans in the survey — 49 percent — said they were enthusiastic about voting, versus 36 percent earlier this month.