For quite a long time there’s been a large and durable partisan gap on the issue of compromise. Generally speaking, Republicans don’t like it: they want politicians to stick to their conservative principles, come hell or high water. If that means shutting down the government or breaching the debt ceiling, so be it.

Democrats are nowhere near as implacable. For whatever reason, they take a more pragmatic view of politics, preferring their politicians to take half a loaf if that’s all they can get.

But that’s all changed. I didn’t see this when it came out a few months ago, but apparently Democrats have finally had quite enough. A Pew poll taken in March shows that Democrats are no longer any more willing to compromise than Republicans:

There are several obvious questions this raises:

First off, this isn’t a pure Trump thing. The share of Democrats willing to compromise went up to 69 percent through mid-2017. Then it collapsed sometime over the next few months. Why?

Whatever happened over the past 12 months to cause this collapse, it didn’t affect Republicans one way or the other. It affected only Democrats.

Possibly by chance, Democrats and Republicans have converged toward each other since 2011: in both parties, about 45 percent now prefer compromise to showdown. Is this meaningful, or just a coincidence?

It obviously wasn’t Trump’s election or his inauguration that caused the Democratic shift toward intransigence. However, it’s easy to think of events later in 2017 that might have sent Democrats over the edge: Obamacare repeal, Charlottesville, the tax bill, pulling out of the Paris accord, the Russia investigation, etc. But at least to me, none of these is an obvious candidate. I feel like the answer lies somewhere else. Any ideas?