How Much do Safe Seats in Congress Contribute to Polarization and Gridlock?

The debate over whether the rise of increasingly safe seats for members of Congress contributes to political polarization remains ongoing.  Political scientists, through empirical studies, tend to conclude there is no significant contribution.  On the ground political actors often assert there is (the issue of safe seats is not necessarily the same as that of gerrymandering — seats could be increasingly safe because of greater geographical sorting that correlates with political views, ie, liberals increasingly concentrate in cities).  In that light, Ezra Klein’s interview today with Robert Costa, whom Klein calls “one of the best-sourced reporters among House Republicans” might be of interest.  The key excerpt:

EK: Why does that happen, though? It would absolutely be possible for liberal members to cocoon themselves in a network of liberal Web sites and liberal cable news shows and liberals activists. But in the end, liberal members of Congress end up agreeing to broadly conventional definitions of what is and isn’t politically realistic. So how do House Republicans end up convincing themselves of unrealistic plans, particularly when they’ve seen them fail before, and when respected voices in the Republican and even conservative establishment are warning against them?

RC: When you get the members off the talking points you come to a simple conclusion: They don’t face consequences for taking these hardline positions. When you hear members talk candidly about their biggest victory, it wasn’t winning the House in 2010. It was winning the state legislatures in 2010 because they were able to redraw their districts so they had many more conservative voters. The members get heat from the press but they don’t get heat from back home.