The last time a sitting Illinois Republican congressperson faced a real primary challenge from a non-incumbent was more than seven years ago, when then-state Senator Kyle McCarter (R-Lebanon) challenged US Representative John Shimkus (R-Collinsville). Even so, nobody really thought McCarter had much of a chance, and, as expected, he ended up losing to Shimkus by more than 20 points. We’ve seen reapportionment-related GOP primaries between congressional incumbents - the most recent being U.S. Representative Rodney Davis’s 2022 crushing loss to fellow U.S. Representative Mary Miller (no relation) - but serious challenges of sitting Republican US Representatives are otherwise fairly rare here.