On Thursday, GOP Rep. Pat Tiberi announced he was leaving the seat he’s held for the last sixteen years to take the job as president of the Ohio Business Roundtable. In a statement, Tiberi said that while he hasn’t yet set a final resignation date, he "will be leaving Congress by January 31, 2018."

The good news for Republicans: this is a pretty solidly Republican district and as such a serious stretch for Democrats to pick off. The bad news: he’s the latest in a string of reliable leadership allies such as Dave Reichert (WA-08), Charlie Dent (PA-08) and Dave Trott (MI-11) to call it quits this year. Even if Republicans ultimately retain control of these seats in 2018, there’s no guarantee that the newly elected incumbents will be team players as Tiberi and these others have been, making Speaker Paul Ryan’s already tough job of wrangling votes even tougher.

The 12th district of Ohio takes in the suburbs and exurbs of Columbus. Back in 2000, when Tiberi was first elected, this was a competitive swing seat. Though Tiberi easily

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