Hillary Clinton, right, was joined onstage by Cecile Richards, left, the president of Planned Parenthood, on June 10, 2016, in Washington. (Bill O’Leary/The Washington Post)

Hillary Clinton engaged her 2016 campaign for president with the kind of hard-line abortion rhetoric and positions that had been noticeably absent from her political repertoire for most of her political career.

Most of us knew Clinton as a moderate abortion rights advocate. She seemed to have genuinely wrestled with abortion as a deeply complex issue over the years, especially as it intersected with her faith. The struggle she said she’s had in protecting the autonomy of women and honoring the value of the fetus seems sincere.

During her Democratic primary battle with Barack Obama in 2008, Clinton’s well-worn position had been clearly established: Abortion should be safe, legal and rare. “And by rare, I mean rare,” she emphasized.

But that position is showing its age. By the November 2016 election cycle, Clinton was all-in for abortion rights. The nuanced rhetoric and talk of making abortion rare was nearly always replaced with talk of fundamental bodily rights and castigation of anyone who wanted to limit abortion.

With the recent release of her tell-all book, “What Happened,” curious readers like me are trying to track down what was behind this historic candidate’s shift on abortion, one that seems to have further polarized her position among voters.

During the campaign, those looking for an explanation for her newfound extremism, a lightbulb may have gone on in January of 2016 when Planned Parenthood endorsed her for president, the first time they had ever endorsed a candidate at the primary stage. A few months later the evidence became even stronger: Planned Parenthood put an astonishing $30 million dollars into a grass-roots program to elect Clinton.

What did Planned Parenthood get for its money? The nation’s biggest abortion rights group got someone who — at least when she was on message — abandoned her younger, more nuanced self on abortion. She did away with her former lines about making abortion rare, which would have implied that abortion is a bad thing and ought to be limited. The new #ShoutYourAbortion campaign displayed so clearly that there’s no room for such nuance in this era of the abortion rights movement.

Abortion in these activist circles can no longer be seen as a tragedy, or the lesser of two evils. No, it must now be celebrated. Indeed, the Democratic platform overseen by the Clinton campaign argued that abortion is “core to women’s, men’s and young people’s health and wellbeing.” Gone were any ideas of limits on abortion, or even that it would be good if there were fewer abortions. The platform even called for Americans to pay for abortion with their tax dollars, repealing the Hyde Amendment.

American politics had never seen anything this extreme from a mainstream party before. Those who knew of Clinton’s past — not only on abortion, but also when it came to accepting money and support from shady places — blamed political maneuvering. They assumed no one who has genuinely struggled as she had with this issue over the years could, in real life, have a position that was so completely without nuance.

Indeed, she had a couple slip-ups during the campaign that seemed to indicate her more authentic views. She not only infuriated her abortion-activist friends by acknowledging the empirical fact that many people are both antiabortion and serious feminists, she let slip on “Meet the Press” that she refers to the fetus as an “unborn person.” The old Clinton seemed to break through the Planned Parenthood performance just often enough to remind us what was really going on.

But now her tell-all book finally gives us her version of events and where she hopes the Democratic Party will go from here. If the theory that she capitulated to Planned Parenthood’s ideology for political reasons is correct, we could expect her to send the signal in this book.

After all, her loss set off a firestorm of often confused debate within the party about how to handle abortion. Indeed, over the past several months there has been some dramatic waffling on this issue, with some Democratic leaders (like Democratic National Committee Chairman Tom Perez) arguing that the extremist position should remain a fundamental commitment, while others (like House Minority Leader Nancy Pelosi (Calif.)) claim that there must be some room for diversity opinion. If the party is going to get the antiabortion independents and Blue Dog Democrats they need to stem an overwhelming tide of political defeats in recent years.

Instead, “What Happened” has put this theory to bed.

In the book, Clinton calls out Sen. Bernie Sanders (I-Vt.) for welcoming antiabortion Democrats in certain districts. She thinks “there’s room in our party for a wide range of personal views on abortion,” but only if a candidate’s antiabortion views don’t actually matter to them enough to influence their politics. “When personal views on abortion become public actions — votes on legislation or judges or funding that erode women’s rights — that’s a different matter,” Clinton wrote.

If this is her actual view, as it now appears to be, it is yet another signal that doubling down on abortion extremism is a path to political disaster, especially turning off voters who are motivated by their faith on this issue.

Even in the few high-profile special elections after Trump became president, we saw that Democratic candidates were able to get close — but not close enough — in part because their opponents were able to tie them to abortion extremism.

Democrat James Thompson ran in just such an election in Kansas this past April. He cut Trump’s margin in the district by more than 75 percent but was unable actually get the victory. Thompson, who campaigned for an empty Congress seat, claimed he lost because his opponents linked him to the current Democratic platform on abortion.

He was bound to a party that is open to the charge that they support abortion on demand for any reason — even on the basis of sex selection — and that such abortions ought to be paid for by those opposed to it.

If Democrats want to win, they should follow the example and strategy of Rep. Ben Ray Luján (N.M.), the Democratic Congressional Campaign Committee chairman and Congressional Hispanic Caucus leader who has refused to accept a fatal abortion litmus test for the party.

But if Democrats wish to continue to hemorrhage legislative seats and governorships, and to lose ground in the cultural debates, then they should follow Clinton’s advice and refuse to open the big tent to even a moderate amount of diversity on abortion.

Charles Camosy is associate professor of theological and social ethics at Fordham University and author of “Beyond the Abortion Wars.”