Marco Rubio Steps up Iowa Visits With Bus Tour, But Plenty of Ground Left to Cover

Marco Rubio starts bus tour Tuesday, aiming for Cruz and Trump.

As things wound down, Earle shook Rubio’s hand on the rope line and told him she had a question; the senator responded with a smile, “I’ll be back a lot and I’ll answer your question then.”

"While other candidates have been largely absent from Iowa in December, Marco is spending time meeting voters and doing what we need to do to succeed in February,” the communications director for Rubio’s campaign Alex Conant told ABC News, while taking a swipe at Iowa co-front-runner Ted Cruz, who hasn’t been in the state for nearly a month.

“Five weeks [until the caucuses] is a long time in presidential politics and Iowa caucus-goers are famous for taking their time. Our sole focus is doing as well as possible and that means spending a lot of time in Iowa over the next few weeks," Conant added.

But winning Iowa isn’t just about the number of visits, fundraising or strong debate performances. It’s about getting bodies to a physical location on a Monday night in the middle of winter and motivating them to stay for at least an hour to caucus on a candidate’s behalf.

But there’s another measurement in that same Quinnipiac Poll that may be worrisome to camp Rubio. When participants were asked whether their mind was made up or might change before the caucus, 67 percent of those supporting Rubio said they could look elsewhere, the highest percentage in that category, compared to Cruz and Trump by 18 points.

At Rubio campaign events throughout Iowa, you don't find many supporters who are 100 percent committed to the 44-year-old. That might not be a bad thing five weeks out.

Welsh says the reason she hasn’t committed to the freshman senator is because of the "large number of strong Republican candidates."

“He’s beginning to get the momentum you need. Being able to raise the money you need. But he has to do well in Iowa," Kincaid said. "It doesn’t do you any good to get behind someone and make contributions to someone who doesn’t do well in Iowa and doesn’t do well in New Hampshire and then falls off the radar.”

Some Republican strategists in Iowa have raised the point that Ted Cruz may be peaking too early. It’s unlikely social conservatives in Iowa who have heavily endorsed Cruz will abandon him before the caucus.

“Just because you’re dating a candidate this weekend, doesn’t mean you're ready to walk down the aisle on February 1,” Strawn, the former head of the Iowa Republican Party, said.

Tim Hagle, a political science professor at the University of Iowa, says having a strong ground game is the key, meaning volunteers working on your behalf and calling people daily to remind them to caucus. Hagle says he's been hearing Rubio's ground game isn't as strong as other candidates, but there’s still plenty of time.

"For Rubio, you would think it seems like a negative that people are coming to his events and they're not committed,” he said. “The positive is that they're coming to hear him. They want to know, is he the guy?"

"I feel like he could be my neighbor,” she said. “A down-to-earth person with no big head. He doesn’t seem to have gotten where he is by stepping on other people.”

Besides Rubio, Earle, who worked for the Dubuque School District for 24 years, says she liked Cruz, but says he’s not as approachable as Rubio.

“I’m hearing in Iowa that Trump and Cruz are the main ones. I think they’re a lot alike in some ways,” Earle said. “This election is really important and we need to put forth a candidate who will take on Hillary and win.”