Heath Mello is the moderate 37-year-old Democrat who was going to help his party make inroads in GOP-controlled Nebraska by becoming the next Mayor of Omaha. Yesterday he lost that race to Republican Jean Stohert who will return to office for another four-year term.

What’s most interesting about this race wasn’t Mello himself but the sharp division he exposed within the Democratic party over the issue of abortion. Mello, who has been a state representative since 2009 is Catholic and had supported some pro-life measures in the past. For many on the left that was a deal-breaker, even though Mello promised to maintain support for abortion rights as mayor.

Bernie Sanders, who is no one’s idea of a moderate, campaigned for Mello last month citing the need for Democrats to be pragmatic about races in Republican territory. “If you have a rally in which you have the labor movement and environmentalists and Native Americans and the African American community and the Latino community coming together saying, ‘We want this guy to become our next mayor,’ should I reject going there to Omaha?” Sanders asked rhetorically. He added, “I don’t think so. It was a great rally, and I hope very much he wins.”

But Sander’s pragmatism was firmly rejected by the president of NARAL. Ilyse Hogue released a statement saying, “Abortion access is not a ‘single issue’ or a ‘social issue. It is a proxy for women to have control over our lives, our family’s lives, our economic well-being, our dignity, and human rights.” In other words, no hint of compromise is acceptable on this issue. That position was given some added weight by the fact that progressive women had taken the lead in ‘The Resistance’ to the Trump administration.

DNC chairman Tom Perez initially offered support for Mello but after getting an earful from abortion supporters reversed himself. “Every Democrat, like every American, should support a woman’s right to make her own choices,” Perez said. “That is not negotiable and should not change city by city or state by state,” he added. Perez even suggested the party would challenge any Democrat who voted against the party line on the issue.

Heath Mello lost the race 53-46, which isn’t extremely close. Still, in a race in which only 96,000 votes were cast the difference was only 6,500 votes. Maybe Mello could have closed that gap with some additional support from the party. Instead, he was publicly castigated for his past position on abortion.

But the issue applies more broadly than one mayoral race in Omaha, Nebraska. As I pointed out last week, there is some evidence, based on data from the 2016 election, that Hillary’s loss was the result of Obama voters who abandoned her to vote for Trump. If accurate, that means Hillary didn’t lose because she failed to turn out her base, but because she failed to persuade swing voters.

It’s easy to see how a debate over abortion becomes a choice between those who are willing to embrace pragmatic persuasion and those who demand party purity. In the case of Heath Mello, the party chose the latter and lost. Democrats may need to embrace persuasion again if they want to come back from their current low point, but at the moment pragmatism still isn’t very popular.