Washington — One of the largest obstacles to the defeat of Donald Trump in the 2020 election is the radicalism of the Democratic Party on the issue of abortion. By forcing Joe Biden to abandon his support for the Hyde Amendment — which currently prevents the funding of abortions through Medicaid — the abortion lobby and activist liberals have taken the first, major step toward reelecting Donald Trump.

The problem here is not only that Biden appears weak and vacillating on an issue of conscience — which he does. Or that he will now be pressured to repudiate every hint of moderation in his 36-year legislative career — though he will be. The Hyde Amendment has played a particularly important role for Catholic politicians. It has allowed them to draw a distinction between permitting abortion and promoting it. Supporting the amendment has let them claim neutrality on abortion even while being effectively pro-choice. For Biden, this fig leaf is now removed. And seeing a 76-year-old man religiously and ethically naked is unappealing.

At the start of Biden’s career — about the time that Roe v. Wade was decided — both political parties contained diverse views on abortion. Early in 1971, for example, the front-runner for the Democratic presidential nomination, Edmund Muskie, was both Catholic and pro-life. During a television interview with David Frost, Muskie said: “I’m concerned about diluting in any way the sanctity of human life. … If it becomes all right to take a life in that stage, then how easy will it be to slip into the next step? Should people in old age who are senile — does it then become legitimate to take their lives?”

Later in that campaign season, after Muskie had dropped out of the race, fellow Democrat Hubert Humphrey attacked the party’s eventual nominee, George McGovern, for being too liberal on abortion. As Daniel K. Williams recounts in “Defenders of the Unborn: The Pro-Life Movement Before Roe v. Wade,” McGovern took the matter seriously enough to run a half-hour television broadcast dealing with issues important to Catholics. At one point, he was shown telling a Catholic nun that abortion should be a matter for states to decide and that he supported some abortion restrictions. McGovern’s first choice to be his running mate, Thomas Eagleton, was strongly pro-life. His second selection, Sargent Shriver, was another pro-life Catholic.

In the 1970s, there were also plenty of Republicans who were pro-choice, including Lowell Weicker, Robert Packwood, Howard Baker, John Tower and Barry Goldwater. In 1975, former first lady Betty Ford called Roe v. Wade a “great, great decision.”

All of this changed when Republicans such as Ronald Reagan actively embraced the pro-life movement, and when Democrats such as Walter Mondale actively embraced the pro-choice movement. A proposed anti-abortion amendment to the Constitution proved particularly divisive. By the 1990s, the parties (at the national level) were in the process of becoming nearly monolithic on opposing sides.

We have come to see abortion as the ultimate culture-war issue, but it is not inherently ideological. The problem with making policy on abortion is this: A conceptus does not appear equal to a person. Yet there is no meaningful distinction between a newborn infant and a fetus the day before birth. Weighing the relative importance of human autonomy and the value of nascent human life is not a typical matter of left and right. Both support for abortion rights and opposition to abortion are argued as matters of inclusion and social justice.

This has left nearly monolithic parties to appeal to a more ethically complex country. A recent Gallup poll found 29% who believe abortion should be legal in all circumstances, 14% in most circumstances, 35% in few circumstances and 18% in no circumstances. So nearly eight in 10 Americans believe that abortion should be available in all or some circumstances. And nearly seven in 10 believe that abortion should be restricted in all or some circumstances.

Joe Biden’s traditional position on this issue — that there should be a difference in government’s role in “the first day and the ninth month” — could effectively appeal to a country with these views. And his opposition to federal funding of abortion was one of the last remaining ways for a Democratic politician to tell Catholics (and others) that their ethical concerns have some degree of merit. Now a Democratic presidential nominee is not allowed even a hint of reticence. Abortion must be supported and funded as a positive good.

The moral question is obvious: How does this allow Biden to live with his Catholic conscience? But the political implications are also relevant. Biden has made it harder — significantly harder — for cultural conservatives who are disturbed by Trump’s cruelty and prejudice to vote for Biden, should he be his party’s nominee.

— Michael Gerson is a columnist for Washington Post Writers Group.