OVERLAND PARK, Kan. (AP) — U.S. Rep. Roger Marshall's audience of about 40 people packed a banquet room in a Kansas City-area bistro. No one wore a mask during his lunchtime remarks about the coronavirus. The Republican nominee for Kansas' open Senate seat put one on later while talking to masked reporters but dropped it for a moment, saying, "I can't breathe."

A few days earlier, Democrat Barbara Bollier invited half a dozen local officials and activists to her first in-person event of the fall campaign. They stood in a socially distanced circle outside an elementary school empty of students...