“Greg Orman has grabbed this race by the throat,” said Chapman Rackaway, a political scientist at Fort Hays State University, noting that Orman leads Roberts in several recent polls. “You just have the sense—I see it every time I talk to people—that politics is broken. When someone reinforces that, saying, ‘Yes, both parties are the problem,’ that really resonates with people right now.”

Control of the Senate could hinge on this unlikely contest between an insistently nonpartisan, Ivy League-educated former consultant and a Republican incumbent who’s spent 33 years in Washington. If elected, Orman says he would caucus with whichever party has the majority. But if there are 50 Republicans and 49 Democrats, he would play tiebreaker: Joining the GOP would give them 51 votes; joining Democrats would give them 50 votes plus the vice president. In that case, Orman says, he would ask both parties to commit to issues like immigration and tax reform, and join the one that agreed. “We’re going to work with the party that’s willing to solve our country’s problems,” Orman said in an interview.