A Public Policy Polling survey this week shows Walker and Rubio in first and second place in Iowa. “The key to Walker’s success is that he’s winning both among voters who are most concerned about electability in the general election and among voters who are most concerned with having the most conservative candidate,” the Democratic firm said in a release explaining the numbers. Rubio and Walker tied in the poll for being the most frequent second choice of voters.

“That’s a really interesting matchup,” said Jack Whitver, an uncommitted state senator who hosted Rubio at his home here for an ice cream social this weekend.

Rubio and Walker differ in many ways—a blue-collar Midwesterner who shops at Kohl’s; the son of Cuban immigrants who is married to a former Miami Dolphins cheerleader – but they are trying to woo an overlapping group of voters. There is a large bloc of establishment-minded activists who do not want to support Jeb Bush for the nomination out of dynasty and electability concerns, and there is a swath of deeply-conservative voters who love guys like Ted Cruz or Mike Huckabee but won’t support them because they want a nominee who they believe can win the general election.

“I don’t know how we characterize our opponent as a relic of the 20th century and then nominate a relic of the 20th century,” said Bob Brownell, a county supervisor in Iowa’s Polk County, which includes Des Moines. “It’s got to be Rubio or Walker in my mind. Walker has that executive experience; Marco doesn’t have that, but what he does have is a 21st century perspective.”