Stronger showings for Trump and Carson suggest there’s a desire in the Republican electorate for an outsider. That’s a hard niche for Walker to fill. While he’s only been a governor since 2011, he’s been a politician most of his adult life, serving first in the Wisconsin legislature and then as Milwaukee County executive.

Walker’s top aides point to the fact that at this time four years ago then-Texas Governor Rick Perry was atop polls in Iowa, before finishing fifth in the 2012 Republican caucuses.

Walker’s team, of course, isn’t alone in building the sort of grassroots network that will be critical to turnout out voters on a cold winter night next year at more than 1,700 precincts.

Chuck Laudner, Trump’s top Iowa strategist and a former executive director of the Republican Party of Iowa, said his candidate is doing things like putting his name on a sprint car at a popular Iowa racetrack to try to appeal to new voters.

“We are going into events that are non-political in nature,” he said. “We have to bring new people in.”