Are Democrats in danger of once again forming a circular firing squad? The Democratic Congressional Campaign Committee (DCCC) is so worried that it’s pressuring weaker candidates in some districts to drop out in favor of well-funded moderates with a better chance of winning in November. California, where a half dozen seats are flippable (one quarter of those needed to gain control), is a particular concern because the state’s “top two” primary system means a large field of Democrats could split the vote and leave two Republicans running against each other in the general election.

Liberal activists say pressure from the DCCC and other Washington types is exactly what they dislike about the Democratic establishment. It’s the same thinking, they claim, that forced the party to nominate Hillary Clinton over Bernie Sanders. Their message: Don’t ram moderates down our throats!

The problem with this argument is that it ignores the mechanics of actually winning elections, which require party discipline and rejection of the narcissism of small differences. Nominating the most liberal Democratic candidate in a Republican district may feel principled but it reeks of moral vanity.