She had barely opened her town hall to questions when Representative Mariannette Miller-Meeks, a Republican from a competitive district in Iowa, was pressed to defend her opposition to abortion rights.
“One of the main functions of the federal government is to protect life,” Ms. Miller-Meeks, who won election in 2020 by just six votes, told a sparse crowd this month in Iowa City, a younger, more progressive part of her district where she…