Throughout her tenure, McCaskill has consistently voted to protect abortion access, but because Missouri has many antiabortion voters, she mostly avoids talking about it on the campaign trail. Recently, though, the issue has become particularly fraught for her.

During the recent confirmation process for President Donald Trump’s conservative Supreme Court nominee, red-state Democrats such as McCaskill and North Dakota’s Heidi Heitkamp spent weeks deliberating over how to vote. Conservatives in their states supported Kavanaugh, but progressives feared his confirmation would spell the end of Roe v. Wade and abortion access in America. “No matter how I vote, there’s going to be a lot of people who are not going to be happy with it,” McCaskill said at the time. The Missouri Democrat ultimately voted against Kavanaugh, but not because of abortion or the sexual-assault allegations against him. Instead, McCaskill said she voted no because of an email Kavanaugh had written to a colleague in 2002, which seemed to suggest that he thought there were “constitutional problems” with limiting campaign contributions to candidates.

“There are some voters that the only issue they care about is outlawing all abortions, and there are other voters that the only issue they care about is keeping access to abortion legal,” McCaskill told reporters ahead of the Senate vote. “What is more common is a large number of people concerned about ‘dark money.’”

In June, as part of an effort to erase some of the gains Republicans had made in the 2016 election, the Missouri Democratic Party had altered its platform to welcome Democrats who oppose abortion. McCaskill, for her part, praised the move. But almost immediately, progressives and abortion-rights activists both inside and outside the state began to protest. By August, Missouri Democrats had removed the provision.

McCaskill’s openness to antiabortion Democrats has earned her criticism from those in her party who argue that all its members should be unapologetically pro-choice. But the senator says she worries that without empowering moderates, Democrats will never regain a majority in both chambers of Congress. “This demand for purity, this looking down your nose at people who want to compromise, is a recipe for disaster for the Democrats,” she told NPR in November. “Will we ever get to a majority in the Senate again, much less to 60, if we do not have some moderates in our party?”

Read: The 2018 midterms could kill the American moderate for good

Others go even further—and say that the party should support only full-throated progressives to be successful. Shortly after winning their elections in November, incoming Representatives Alexandria Ocasio-Cortez of New York and Rashida Tlaib of Michigan announced that they would work with Justice Democrats, a progressive political-action committee, to recruit working-class candidates to challenge more conservative Democrats in the House.