When gardeners apply a litmus test to their soil, their goal is to create a flourishing garden. When politicians use a litmus test, usually their goal is to shackle a candidate to the party’s non-negotiable policy positions. A case in point is the Democratic Party’s litmus test on abortion. Its unyielding support of abortion was vividly on display in Omaha, Nebraska, during the recent mayoral primary. Former Nebraska State Sen. Heath Mello, a Democrat, ran in the non-partisan primary race against Jean Stothert, the Republican incumbent. As this issue of Chicago Catholic goes to press, they face each other in the May 9 election for mayor. Candidate Mello drew the support of Sen. Bernie Sanders of Vermont. Sanders, Rep. Keith Ellison (D-Minnesota), deputy chair of the Democratic National Committee, and Jane Kleeb, chair of Nebraska’s State Democratic Party all joined Mello at a campaign rally. Sanders, though not officially a Democrat (he caucuses with the Democrats but is officially independent), is working hard to unite the party around the economic issues that drove his 2016 presidential campaign. Since the election, Sanders has been leading a "Unity Tour" with the DNC to help elect more Democrats across the country and to recapture city and state offices that were once the backbone of the party. Mello welcomed Sanders’ support in the Omaha mayoral contest. But not all Democrats did. Why not? Because Mello is a pro-life Democrat. Sanders, who is pro-choice, doesn’t care that Mello describes himself as pro-life and voted in the state senate to support what some say are abortion restrictions but others see as legitimate informed-consent and safety procedures. Sanders wants Democrats to focus on economic issues, issues that arguably won Donald Trump the presidency. Showing up at a Mello rally, Sanders in effect indicated that abortion should no longer be a litmus test for Democrats. That did not play well with pro-choice organizations, such as NARAL and Planned Parenthood, which loudly and strenuously criticized Sanders and Ellison. How far have their objections carried? The new head of the DNC, Thomas Perez, who supports Sanders’ unity tour, waffled, reinstated the litmus test, then waffled again ("Tom doesn’t believe in litmus tests and never said he doesn’t support pro-life candidates," a DNC aide reportedly said). Sen. Elizabeth Warren (D-Massachusetts) jumped in to support Sander’s argument: economic issues come first. More recently House Minority Leader Nancy Pelosi (D-California), in a Washington Post interview, declared the abortion litmus test, "a fading issue." They all recognize, as Hillary Clinton did not, that the emphasis on abortion and other cultural issues drove many of the Democrats’ traditional constituencies away. Allowing both pro-life and pro-choice candidates to run under the Democratic banner has the virtue of letting voters, rather than party leaders and big donors, choose the candidates. The Omaha imbroglio may be a small ripple in a big storm. Yet Sanders, Warren and Kleeb, by supporting Mello and welcoming pro-life candidates, give heart and encouragement to those many "Democrats" who have long seen themselves as unwelcome, in effect, "politically homeless" in their own party. If Nebraska Democrats succeed in electing Mello and others like him, they will help break the abortion litmus test that has shackled Democrats for far too long. Steinfels is a former editor of Commonweal and Church magazine.