Why won’t Democrats let anti-abortion progressives under their tent?

Is it possible to be a good progressive and oppose abortion? This long-simmering question was brought to the fore recently when Democratic National Committee Chairman Tom Perez and Sen. Bernie Sanders (I-Vt.) announced their support of Heath Mello, a candidate for mayor of Omaha who is also, inconveniently, antiabortion.

Under pressure from abortion rights groups, Perez quickly walked back his support for Mello and said that being pro-choice was “not negotiable” for Democrats. That reversal was in turn rebuked by a chorus of high-ranking Democrats, including House Minority Leader Nancy Pelosi (Calif.) and Senate Minority Leader Charles E. Schumer (N.Y.). In the end, Perez walked back his walk-back, announcing there was no litmus test after all.

But is there? Should there be? Increasingly, abortion opponents hear a resounding yes. The message they get from progressive activists and commentators, if not from Democratic Party leaders, is increasingly hostile: As much as the party professes to be a big tent, those who oppose abortion rights aren’t really wanted.