It’s too early to tell, of course, whether Feenstra represents a serious challenge to King’s 2020 prospects. For one thing, despite his decade of public service, Feenstra is a novice to the game of campaigning: In both of his previous elections he ran unopposed.

But there’s ample evidence to suggest that King is more vulnerable to a primary challenger than ever before. In his first eight election campaigns, his worst ever showing was in 2012, after his district was reapportioned, leaving him with a bluer map and a heap of unfamiliar constituents. Nevertheless, he still defeated former Iowa first lady Christie Vilsack by eight points. By 2016, he was firmly back in control, defeating Demorat Kim Weaver by nearly 23 points. But in 2018, following months of controversy, King limped to the finish against a rookie challenger, J.D. Scholten, whom he held off by only 3.4 points—despite enjoying a 14-point district-wide edge in party affiliation. Even that he managed only by painting a stark contrast between himself and his opponent on social issues like abortion.