The 115th Congress has seen a high number of Republican retirements.
So far, 22 House Republicans and three Republican senators plan to retire at the end of the year. That doesn’t include eight more Republicans who have already resigned from Congress.
By comparison, only nine House Democrats and not a single Senate Democrat have announced plans to retire at the end of the 115th Congress, which concludes in early January 2019. Several Democrats — most notably, former senator Al Franken — have resigned already from Congress but still fewer than the Republican total. In addition, a dozen Republican House members are running for either governor or the Senate. Only seven Democrats are doing the same.
The practical effect is that Democrats have more opportunities in the 2018 elections. Open seats are usually harder to defend than those held by incumbents. Looking at elections for Congresses back to the 101st provides some useful comparisons.
Retirements by House members since 1990
Totals are for House members who retired (or plan to retire) at the end of the Congress. The table excludes those who died, resigned or ran for other offices.
In the early 1990s, the 102nd Congress saw the greatest number of retirements — not surprising between the effects of redistricting and the House banking scandal. More Democrats than Republicans retired at the end of the session, but the House had a Democratic majority at the time.
Better comparisons for the current Congress are the 103rd and 110th Congresses. In both cases, one party had a much higher number of retirements than the other. In both cases, the party with more retirements suffered significant losses in the election. 1994, of course, saw Republicans take control of the House for the first time in 40 years. 2008 saw the Democrats increase their control of the House as Barack Obama was elected President.
So the fact that more House Republicans are already declining to seek re-election after this session than in any Congress since 101st is probably not a good sign for the Republicans.