Why the Republicans Resist Compromise

By NATE SILVER

The chart that I’m going to show you is one of the more important ones that we’ve presented at FiveThirtyEight in some time. It helps explain a lot of what’s going on in American politics today, from the negotiations over the federal debt ceiling to the Republican presidential primaries. And it’s pretty simple, really, although it took me some time to track down the data.

Here’s what the chart will show: The Republican Party is dependent, to an extent unprecedented in recent political history, on a single ideological group. That group, of course, is conservatives. It isn’t a bad thing to be in favor with conservatives: by some definitions they make up about 40 percent of voters. But the terms ‘Republican’ and ‘conservative’ are growing closer and closer to being synonyms; fewer and fewer nonconservatives vote Republican, and fewer and fewer Republican voters are not conservative.