Many of the most senior members of the House are departing at the end of this year. With the retirement of Paul Ryan, Republicans will be electing their third speaker in three years (if they manage to maintain control). In addition to the speaker, of the 21 members who started this Congress as House committee chairmen, 10 will not be returning next year.

But it’s not just the party leadership. Back-bench tea party members are streaming out of the Congress, too. Of the 87 tea party members elected in 2010, nearly half have already left the House or have announced their retirements.

This dramatic turnover in the composition of Congress has occurred at the same time as the emergence of a newly rigid partisanship. The convergence of these two forces—an inexperienced Congress and political tribalism—has hastened the decline of institutional politics in our country, particularly in Congress. Loyalty to party is now the most important thing.