When Republican Scott Walker arrives Monday at Iowa's state fair, he'll land in an unfamiliar position: he won't be the front-runner in the state that holds the first presidential nominating contest.

Like most every other candidate in the historically crowded field, the Wisconsin governor's standing in state and national polls has been hurt by the summer surge of billionaire Donald Trump, the party's front-runner.

No state is more critical to Walker's future than Iowa, where media expectations about his candidacy have grown to the point that anything short of a win in the Feb. 1 caucuses is likely to be viewed as a serious momentum killer.

“I run into people who support him, but I think the polls reflect the fact that everyone is just struggling to get traction, outside of the three non-politicians,” said John Bloom, Republican Party treasurer in Polk County, the state's largest.

Bloom, who is undecided in the race, was referring to Trump, retired neurosurgeon Ben Carson, and former Hewlett-Packard CEO Carly Fiorina. He's not ruling out the possibility of a Trump win in Iowa.

“If you had asked me a month ago, I would have said no,” he said. “But I think there is more commitment there to something. I don't know if it's for Trump, or this rebellion against our leadership.”

Walker, who has enjoyed a consistent lead all year in Iowa, dropped to third in the most recent CNN poll. He was backed by just 9 percent of likely caucus participants, below Trump at 22 percent and Carson at 14 percent.

It's a dramatic fall for a guy who led in a Bloomberg Politics/Des Moines Register Iowa Poll with 17 percent as recently as late May. That was approaching the level of support—roughly 20 percent—that most party insiders agree could win the caucuses in a 17-candidate field.

Walker is the man with the most to lose from Trump's Iowa rise because he's counting on a win in the state to provide momentum in subsequent contests where Trump and former Florida Governor Jeb Bush are almost certain to be better financed.

“We are focused on the fundamentals of caucus organizing on the ground, not a week of snap polls,” said David Polyansky, Walker's senior Iowa adviser. “Governor Walker will continue to share his record of success and his vision for America, and his team will continue to focus on building an operation that is capable of carrying him across the finish line next year.”

For now, Walker has four paid staff members in the state, two consultants, and one campaign office, all numbers that will grow as the fall progresses. His campaign has 65 members on its Iowa leadership team, including more than one-third of the state's senate Republicans and numerous other current and former elected officials, business leaders and party activists.