Inflation Remains Voters’ Top Concern. Can Republicans Keep Their Focus?

Democrats and Republicans are running parallel campaigns, with one party emphasizing abortion and democracy, the other inflation and the economy — and both talking past each other.

Zach Nunn, an Iowa Republican challenging one of the House’s most vulnerable Democrats, had been talking for months about rising prices when a Texas congressman two weeks ago invited him to visit the Mexican border — to see the fentanyl confiscated, hear tales of dying migrants and witness overwhelmed border agents.

Mr. Nunn took it all in, he said. Then, he went back...