It seems like every time I turn around another Senator or Representative is not going to run for re-election. Most seem to be retiring, while a few are declaring for another seat. So I went looking and found that Ballotpedia has an excellent summary page of these announcements so far.
I don’t know how this compares to previous elections, and I didn’t find anything for previous years on Ballotpedia. Just to summarize, 3 Republican Senators are not running for re-election, and 15 Democratic and 34 Republican Representatives are not running for re-election.
Without the context of previous years, it’s hard to really speculate on what’s going on, but it sure feels like a lot of Republicans are realizing the next mid-terms are going to be very difficult, no matter what VP Pence might be thinking, and sometimes it’s easier to let the next generation carry the fight.
Then there’s the discouragement of realizing that the leadership is basically incompetent (I’ve seen sentiments roughly approximating that in print somewhere), realizing that power isn’t all it’s cracked up to be, and that sort of thing.
Incumbents are hard to beat. The large number of Republicans heading out the door suggest a lot of opportunities for the Democrats.