A special election next week in Ohio’s 12th Congressional District is the last big electoral test before November’s election, a showdown in a once deep-red suburban House seat that Donald Trump won just two years ago by 11 points.

Now, however, both parties view the race between GOP nominee Troy Balderson and Democratic nominee Danny O’Connor as a toss-up — and that’s a warning sign for GOP candidates already bracing for a difficult election environment, especially in suburban districts that will help determine control of the House this fall…

“In a good year, in a good environment, you probably wouldn’t worry so much about this district,” said Scott Jennings, a veteran Republican strategist who ran Mitt Romney’s Ohio operation in 2012. “In a bad year, a bad environment, it’s exactly the kind of district you worry about, particularly because of the suburban elements that exist in this district.”