So a debate that once gripped the White House has ended up here, nestled beside corners of Illinois and Wisconsin — and it has animated the politics of a state that was thought to be in the bag for President Donald Trump but now appears to be a seesaw battle, with Trump making a last-minute visit to Dubuque on Sunday.

The dispute has reached the most literal of grassroots — a rural county where a retiree from the nearby John Deere factory has spent months battling with an electric utility project manager, through Zoom calls and open letters, over whether the county should order nearly 100,000 residents to wear face coverings.

“We feel that a County Wide Mask Mandate is reasonable and necessary to protect the health of all citizens within Dubuque County,” the retiree, Tom Bechen, who chairs the county’s all-volunteer board of health, wrote to the county’s three elected supervisors last week — launching yet another gambit to win them over. Since Bechen’s board began pushing the supervisors to adopt a mask mandate on Aug. 5, the county’s confirmed Covid-19 cases have more than tripled and deaths doubled.