America’s largest annual anti-abortion protest drew tens of thousands of people to Washington in one of the most precarious years in decades for reproductive rights.

The March for Life demonstration has been organized since 1973 and Roe v Wade, the landmark supreme court decision that legalized abortion nationally. In the decades since, the march has become a tradition for many with a conservative or religious objection to abortion, a ritual they hope will return America to a time when abortion was clandestine, even as many countries around the world liberalize abortion laws.

“I’m very passionately Catholic, and so it goes against everything I’ve ever been taught in my life,” said Shawna Queen, a mother from Portsmouth, Ohio, who brought three generations of her family with her. She started to cry while describing abortion. “I just think it’s a travesty that we kill the unborn,” she said.

Attendance hit a high-water mark in 2009, just after Barack Obama’s inauguration. But this year will hold special significance for many.

Where once there was doubt about Donald Trump’s anti-abortion bona fides – he once called himself “very pro-choice” – that has long been forgotten, at least publicly. Red Make America Great Again hats were omnipresent at Friday’s demonstration.

Trump this year became the first president ever to address the march in person. In previous years, Mike Pence, the vice-president, attended, and Trump relayed video messages to attendees.

The president’s administration is responsible for putting abortion rights on exceptionally shaky ground. A conservative-leaning supreme court, with two justices of Trump’s choosing, is set to hear its first abortion case in March. Some signs at the protest read “Most Pro-life President Ever” with an image of Trump in red.

A majority of Americans still support abortion rights, and oppose efforts to overturn Roe v Wade: those opinions have shifted little in the decades since abortion was legalized. However, where supporters of reproductive rights considered the issue a settled matter, opponents saw Roe as a target to aim at.

Emboldened by Trump’s anti-abortion rhetoric, states have worked to overturn Roe v Wade and undermined states’ rights and services along the way.

Protesters listen to Donald Trump address the crowd. Photograph: Olivier Douliery/AFP via Getty Images

A wave of the strictest anti-abortion laws in decades swept across the south and midwest last year. Many laws banned abortion at the sixth week, before most women know they are pregnant. The laws are all unconstitutional, as long as Roe stands, and none have gone into effect.

“My hope is there will be a law that will not allow abortion to continue happening,” said Gladys Kohr, who came to the march in a full-sized bus wrapped in pro-Trump images. Abortion “should be illegal”, she said.

Behind Kohr, the bus sported pro-Trump memes. One image showed Trump’s head superimposed on the body of a boxer, and said “Ready for Round Two”. In another, Britain’s Queen Elizabeth wore a Maga hat and gave a thumbs-up.

Kohr said she would support punishment for women who have abortions, and doctors who perform them – “something very severe”. But she said women should be given information about abortion before being allowed to undergo the procedure.

Even so, the crowd was not monolithic.

Pat O’Kane from California, who attended with a group called Feminists for Life, was wary of the movement’s adulation of Trump. “I sort of take the biblical position – we should not put our faith in princes,” she said. “I don’t think any one president, or even a succession of presidents, is necessarily the answer.”

One surprise was the common ground between the anti-abortion and pro-choice movements on other women’s issues. Many attendees said they supported paid maternity leave, usually considered a progressive cause. The US is the only developed country that does not mandate maternity leave. Many also supported better workers’ protections for pregnant women.

But it is the primacy of abortion has turned the issue into a gaping political wound. For many protesters, abortion represented their No 1 voting issue, eclipsing policies that might otherwise support pregnant women and mothers.

Anti-abortion leaders have sought to blur this image. This year’s theme is “Life empowers: pro-life is pro-woman”. It is meant to commemorate the centennial of women’s right to vote in the US, ratified in 1920.

Queen, from Ohio, said: “I absolutely think that maternity leave should be an everyday practice in our country. I always vote. [But] I don’t even have a party any more. I vote on how I can sleep at night,” she said, referring to abortion. Most often, that means voting Republican.

Republicans have attempted to capitalize on this apparent soft spot, but have only introduced plans to allow workers to borrow against their future retirement benefits. Such proposals have not received any broad-based support.

Kaleb Pandorf, 20, from Smyrna, Tennessee, said he supported same-sex marriage and, unlike much of the crowd here, does not consider himself a Christian. But if a candidate were to promise to end abortion and same-sex marriage, he would value abortion above all, he said.

“As much as I hate to say it, I’d have to, I’d have to support him,” he said. “Because he sees the wrong in killing a child.”