Iowa City, Iowa - Some presidential candidates have been campaigning here for a year. Airwaves, mailboxes and websites here are crammed with attack ads and sunny spots berating, condemning and propping up every one on the ticket. And many of the voters interviewed here have seen each of the top contenders multiple times.

Yet, somehow, there are still some voters here who are undecided. And the campaigns crisscrossing Iowa in the final days ahead of the Monday caucus are honing in on the uncommitted.

Most polls show a two-man race between Donald Trump and Texas Sen. Ted Cruz on the Republican side, as well as a tightening contest between Hillary Clinton and Vermont Sen. Bernie Sanders across the aisle. But there's a solid group that is still wavering.

The latest Quinnipiac University poll, for instance, shows that 2 percent of Iowa Republicans are undecided - a statistically irrelevant margin. But it also showed that nearly 39 percent of those who name a candidate say they might change their mind.

"It all comes down to turnout. And with four in 10 likely caucus participants saying they still might change their mind, this is an especially volatile race," said Peter Brown, assistant director of the poll.

They’re fighting for the likes of Jill Holmes. She’s an undecided Republican who will most definitely caucus for someone on Monday. As the clock ticks down, she’s leaning toward retired neurosurgeon Ben Carson - but she’s open to a last-minute change.

“I thought I was going to support (Ohio Gov. John) Kasich until I heard Carson. And then I decided that I have an opportunity to hear five out of the seven top contenders without having to go far,” she said. “So I’m going to seize the opportunity. I think we don’t realize the opportunity we have.”

She was among about 200 Iowans who packed the University Club in Iowa City to hear New Jersey Gov. Chris Christie on Saturday morning. The same venue hosted Carson and businesswoman Carly Fiorina in the last five days, and Holmes said many of the voters who crowded into Christie’s town hall meeting were also at the earlier events.

“Many of us still haven’t made up our minds,” she said.

And, after hearing Christie’s roughly hourlong town hall meeting, neither had she.

“He’s pretty convincing, isn’t he? I guess I got to throw him in the mix. I have a pretty strong hunch that Monday night I’ll cast a vote for a governor,” said with an exasperated look. “Jeez, does that make me sound wishy washy?”