Four scandal-plagued House Republicans whose seats should be gimmes for the GOP have instead turned their races into unexpected battlegrounds. Why it matters: These aren't districts you'd expect to be in play — Donald Trump carried all four comfortably in 2024. But the incumbents' ethical troubles are making Republicans spend time and money defending the seats — in a cycle where neither party has any room for error.Chuck Edwards (R-N.C.) dropped his reelection bid after the Ethics Committee found he violated House rules by sexually harassing female aides and creating a hostile work environment. That's set off a scramble to find a replacement just three months before the election. The race was shifted to "toss-up" last week by Sabato's Crystal Ball, even before the ethics report was released. Trump won Edwards' district by 9.5 points last cycle.Whoever North Carolina Republicans choose on Monday night to replace Edwards will have a short runway to fundraise and introduce themselves to the district.Max Miller (R-Ohio) is accused of assaulting his ex-wife and their child, allegations he denies.Even Trump expressed doubts to Miller that he can win, Axios reported this week. But he's been defiant amid calls for him to drop out.Democrats are pinning their hopes on ironworker Brian Poindexter, a progressive populist backed by Sen. Bernie Sanders (I-Vt.).Trump carried the district by 11 points two years ago.Cory Mills (R-Fla.) remains under an active Ethics Committee investigation over allegations that center on domestic abuse, stolen valor and financial misconduct, all of which he denies.Trump won Mills' district by 13 points in 2024, but Mills is facing a tough primary fight. Reps. Anna Paulina Luna (R-Fla.) and Mike Haridopolos (R-Fla.) officially backed Mills' primary challenger, Ryan Elijah. Haridopolos told Axios Wednesday that Elijah is a "true family man who can win in November in this safe Republican seat." Multiple Democrats are vying to challenge Mills, but party leadership has lined up behind former NASA Chief of Staff Bale Dalton.Andy Ogles (R-Tenn.) had his phone seized by the FBI in 2024 as part of an investigation into his campaign finances.The Justice Department dropped the case after Trump returned to office last year, but the probe has left Ogles politically vulnerable.Democratic leadership's top-flight recruit in the district, Columbia Mayor Chaz Molder, has a 3-to-1 fundraising advantage over Ogles.What they're saying: Viet Shelton, a spokesperson for the Democratic Congressional Campaign Committee (DCCC), projected confidence that all four of these districts are very much in play."Vulnerable House Republicans mistakenly think that no matter how awful their behavior is, they are untouchable," he said in a statement."Voters in these districts are pissed over higher costs, Republicans' broken promises, and are ready to reject these scandal-plagued members, who've made voters' lives worse." Between the lines: There's a chance Ogles, Mills and Miller don't make it to the general election.Ogles and Mills are both facing primary challenges from GOP rivals who have out-raised them.Miller has until next week to withdraw from the ballot and Republicans are eyeing contingency plans in case he bows to growing pressure.The bottom line: "If all four of them are on the ballot, it's a lot more of a pain in the ass," one GOP operative told Axios shortly before Edwards dropped his bid.