Well, their prayers have been answered. Today we have a solidly liberal Democratic Party and a solidly conservative Republican Party. The voters get to make a rational choice between two pretty clearly defined alternatives.

Party leaders in Congress exert impressive discipline over their colleagues. Senate Democrats got all 60 Democrats to vote for Obamacare despite negative polls. Republican Speaker John Boehner got almost all House Republicans to back Paul Ryan’s budgets.

The two parties compete vigorously and on close to even terms. A Republican president was re-elected with 51 percent of the vote in 2004, a Democratic president re-elected with 51 percent in 2012.

And almost all voters vote straight tickets. Clark Bensen of Polidata has crunched the presidential results by congressional district for National Journal and the Almanac of American Politics…

So now political scientists lament gridlock and polarization and partisanship and reminisce about those (mostly mythical) days when politicians of both parties got along.