Zach Lahn’s win in Iowa is a rare rebuke to Trump, who still has an iron grip on the party
While president’s last-minute endorsement of Randy Feenstra failed, he has enjoyed successes in Texas, Indiana and Kentucky

TL;DR
- Zach Lahn won the Iowa Republican gubernatorial primary, narrowly defeating Congressman Randy Feenstra.
- Feenstra had received Donald Trump's "Complete and Total Endorsement", a rare occurrence of a Trump-backed candidate losing.
- Trump's endorsement has recently been successful in primary challenges against Republican incumbents in other states.
- Lahn, a farmer and businessman, campaigned against big agricultural businesses and has embraced some "make America healthy again" policies.
- Democrats believe they have a strong chance to win the governor's race due to Trump's unpopularity and the strength of Democratic candidate Rob Sand.