For Democrats with eyes fixed on the midterms, the months since the 2016 election have been filled with soul-searching about the most promising paths to victory in 2018. This week, Rep. Ben Ray Luján, head of the Democratic Congressional Campaign Committee, made some news when he said in an interview with The Hill that the organization wouldn’t take a candidate’s stance on abortion into account when allocating campaign funds. The move has angered some on the left and renewed questions about what ideological deviations from Democratic orthodoxy the party should tolerate as it tries to win back voters who swung for President Trump in last year’s election.

Activists and some prominent Democrats took umbrage with the DCCC’s stance when news of it surfaced this week. Cecile Richards, head of Planned Parenthood, wrote in a tweet, “Women deserve access to safe, legal abortion no matter if their state is red or blue — it’s a constitutional right that can’t be traded away”; and ThinkProgress talked to abortion rights activists who felt undermined by the move. Former Democratic National Committee chair Howard Dean, who headed the organization during its 2006 “50 state strategy” push to be competitive, even in conservative states, tweeted out the Hill article and said, “I’m afraid I’ll be with holding support for the DCCC if this is true.”

But the DCCC signal on abortion is in keeping with some of what Sen. Bernie Sanders has been pushing for — that the party emphasize its economic message over its cultural one. It’s this philosophy that led Sanders to campaign this past spring for a Democratic mayoral candidate in Omaha, Nebraska, who voted for abortion restriction measures during his time in the state Senate.

The debate isn’t just lip service about how to attract Trump voters — it’s indicative of a split that already exists within the party. A look at the numbers shows Democrats don’t all feel the same about abortion rights. In 2017, polarization doesn’t just happen across party lines, but within parties themselves.

In 1995, about 66 percent of the overall Democratic electorate believed that abortion should be legal in most or all cases. Since then, Democrats overall have shifted towards greater comfort with abortion. In 2017, 75 percent said they think it should be legal in most or all cases, according to a Pew Research Center poll.

But that shift hasn’t occurred across the board within the party. The last couple of years have seen approval for abortion shoot up dramatically among white Democrats and those who identify as ideologically liberal. But black Democrats and ideologically moderate or conservative Democrats have moved more slowly in their approval rates.

Angry reaction to Luján and the DCCC’s decision against an abortion litmus test for campaign funds comes in part because ideological liberals now make up more of the Democratic Party. Those liberals’ approval rates for abortion have increased dramatically since 2015, indicating perhaps a renewed interest in the abortion rights cause since the rise of Trump.

According to Gallup, liberal affiliation within the Democratic Party has increased by around one percentage point every year since 2001, when it was 30 percent, through 2016, when it was 44 percent. And in just the past two years (the most recent presidential election cycle), self-described liberal Democrats have become dramatically more supportive of abortion rights: In 2015, 78 percent of liberal Democrats thought abortion should be legal in all or most cases, and by 2017, that number was at 88 percent, a dramatic jump.

White Democrats made similar movements in those two years: In 2015, 74 percent of them favored abortion, and in 2017, that number was at 83 percent. Black Democratic voters have also increased their support for abortion rights over the last decade, but continue to lag behind the percentage of white Democrats who favor abortion rights. Views on abortion among black Democrats (who are less likely than white Democrats to identify as liberal) haven’t substantially changed over the last two years. In 2015, 64 percent of black Democrats thought abortion should be legal, and in 2017 that number had only moved to 66 percent. That’s a 2-percentage point swing compared to white voters’ almost 9-point swing during the same two years.

In a party that is growing increasingly liberal, the argument to play to an emerging base of voters activated by Trump is compelling. Dean told FiveThirtyEight that he sees cultivating the strength of youth movements as key. “The big trick with this age group is to organize them, stop them from being ad hoc,” he said. “We need to focus on our principles and then sell our principles to people who are inclined to work with them.” For Dean, being in favor of abortion rights is one of those principles.

But if the focus for Democrats is the short-term need for 2018 wins, the DCCC and Sanders also have a strong case. Even setting aside whether or not candidates with more moderate views on abortion will win back areas Democrats lost to Trump, abortion doesn’t seem to particularly animate a key group that Democrats need to see turn out in 2018: black voters. Although the latest Pew Research Center poll showed that most black Democrats are pro-abortion rights, only 7 percent said the party should limit its support to pro-abortion rights candidates in a recent YouGov poll. White Democrats, on the other hand, prioritized the issue of abortion rights more strongly, with 35 percent of them saying that the party should limit its support to only these types of candidates.

What does seem clear is that as the road to 2018 unspools, the Democrats might need to brace for their own culture war over the culture wars.