"Under my administration, we will always defend the very first right in the Declaration of Independence, and that is the right to life," Trump said in the White House Rose Garden, in a speech that was broadcast to the marchers gathered near the Washington Monument.
The march - which typically draws busloads of Catholic school students, a large contingent of evangelical Christians and poster-toting protesters of many persuasions - falls each year around the anniversary of the 1973 Roe v. Wade decision that recognized a legal right to abortion and intends to pressure Congress and the White House to limit legal access to the procedure.
Trump said he was "really proud to be the first president to stand with you here at the White House;" Ronald Reagan and George W. Bush addressed the march by telephone when they were in office.
Megan Ensor, who came from Atlanta to attend her first March for Life, expressed her enthusiasm that Trump took the time to speak to the marchers. "When it comes to the greatest moral evil of our time, the question that is most important is that he cares. . .. When he comes today, that's a good thing. We don't have to agree with him on everything," she said.
Anna Rose Riccard, 25, works for anti-abortion organizations and called the president's appearance not a boon but an "unfortunate distraction." Riccard, of Alexandria, Virginia, doesn't believe the anti-abortion cause is a priority for Trump, and she saw fellow Catholics disagreeing on social media about his appearance.
Trump, however, touted his administration's anti-abortion policies, including new orders on Thursday and Friday establishing an office to support medical professionals who do not want to perform abortions and making it easier for states to direct funding away from Planned Parenthood.
Most leaders of the antiabortion movement don't blame Trump for what they perceive as a lack of progress; they fault Republicans in Congress for inaction.
"It's because of the Senate. I put the blame with the Senate," said Jeanne Mancini, president of the March for Life, said in an interview last week. "I think that some of our members of Congress are afraid to be courageous on these issues."
Though Trump said Friday that "Americans are more and more pro-life; you see that all the time," American views on abortion have remained quite steady for decades. Since the mid-1990s, about half of citizens, give or take a few percentage points, have said abortion should be legal in all or most cases, while 40-odd percent have said it should be illegal in all or most cases.
Last year, the March for Life fell just days after Trump's inauguration, and the tone was ebullient. Marchers believed they were heralding a new administration that would prioritize limiting abortion. Mancini said then that she had four goals for policy in the president's first year in office: appointing an apparently antiabortion Supreme Court justice, defunding Planned Parenthood, codifying the annual Hyde Amendment that restricts federal money from funding abortions and passing a law banning abortion in many cases after 20 weeks.
A year later, only the first of those four goals has been accomplished.
Bills to make the Hyde Amendment permanent and to ban certain late-term abortions passed in the House but are unlikely to pass the Senate. Both chambers of Congress tried to defund Planned Parenthood in their unsuccessful efforts to pass a health-care bill.
Even abortion rights supporters are surprised that antiabortion policies haven't made more headway in the past year.
"I think it goes to show how the Republicans just didn't have a plan, in many ways," said Heather Boonstra, director of public policy at the Guttmacher Institute.
The White House has advanced several policies through executive orders rather than legislation, starting with an expanded version of the Bush-era Mexico City policy, which bars U.S. funding to public health organizations that promote abortion overseas and which Trump reinstated upon taking office. On Thursday, the day before the march, Trump announced another policy that pleased antiabortion activists - a new office meant to protect the rights of medical professionals who don't want to participate in abortions because of their religious beliefs.
In his speech Friday, Trump noted those actions, and boasted about the stock market and unemployment rates as well. He called to the podium a mother who became pregnant at 17 and later went on to help establish a facility to support homeless pregnant women.
Trump repeated a claim he made during a presidential debate against Hillary Clinton in 2016 - that a fetus in "a number of states" can be aborted "in the ninth month."
"It is wrong. It has to change," he said about those late-term abortions. As the Post's Fact Checker pointed out in 2016, 89 percent of abortions occur in the first 12 weeks and only 1.2 percent occur after 21 weeks of pregnancy, according to the Guttmacher Institute. All but seven states prohibit some abortions after a certain point in pregnancy, making "ninth month" abortions exceptionally rare and largely banned already.
At the marchers' noon rally east of the Washington Monument, the White House satellite appearance was among a slate of speakers, including House Speaker Paul Ryan, R-Wis.
The crowd gave the rock star treatment to Ryan, greeting him with whoops and applause. "How grateful are we to have a pro life president back in the White House!" Ryan said.
"One thing that gets lost is how compassionate the pro-life movement is," he said. "To help women who have gone through the pain of abortion, to help single mothers, to give them resources through thousands of pregnancy centers: this is the face of the pro-life movement."
Ahead of the march, anti-abortion groups around the region hosted events on Friday morning - huge youth Masses full of screaming teenagers, a meeting on legal strategies to limit abortion and a conference in the basement of a downtown hotel where the emphasis was on expanding the idea of "pro-life."
Hundreds of people at the Evangelicals for Life conference wandered booths about prison ministries and health care and heard speakers talk about the importance of adoption and serving refugees.
Popular evangelical author and speaker Ann Voskamp talked to a crowd of largely young white listeners about a "robust pro-life ethic. . .. We are for both humans in utero and humans in crisis. This is us."
The message echoed a talk on Capitol Hill Thursday, where the Rev. Samuel Rodriguez, one of Trump's evangelical advisers, stood with House Minority Leader Nancy Pelosi urging Congress to protect undocumented young adults. Noting that the March for Life would be the next day, Rodriguez said the two topics were linked as "life" issues.
Jessica Ponce, 26, marched at the very front of the pack with fellow parishioners from the Archdiocese of Mobile, Alabama. She said this is her first march, and a poignant one, because she just learned she is pregnant. A native Mexican who is now a permanent resident in the United States, she said that to her, "pro-life" means taking care of all human beings, including immigrants and refugees.
"It's not possible to care for people if you are separating families, and parents cannot defend the lives of their children if they are not able to stay together," she said.
In an effort to make the same point, a group of Franciscan priests stood near the front of the stage during the rally. When Trump appeared on the screen, they raised banners saying: "Keeping families together is pro-life! Keep God's dream alive!"
"I'm here to stand for the integrity of my faith and of the gospel. I'm not willing to sacrifice that for political expediency," said the Rev. Jacek Orzechowski, a community organizer with Catholic Charities of Washington. "For someone to say they're pro-life but display callous policies that tear families apart is reprehensible."
A Catholic priest from New York City said some in his parish - a heavily Central American congregation that includes many undocumented immigrants - didn't come to Washington out of fear. The priest, who said he was afraid to use his name, still praised Trump's talk at the rally. "We put our faith in no man. Our faith is in Jesus."
About 50 demonstrators staged their own rally outside the Smithsonian Air and Space Museum rather than joining the main rally on the Mall, to protest Trump's address. They said their belief that life begins at conception comes from scientific research on fetal development, not from faith, and they wanted their "I am a pro-life feminist" signs to indicate that the anti-abortion movement is not just "a bunch of priests," as Destiny Herndon-De La Rosa put it.
"Let's put some secular, pro-life, bad-ass feminists up front," she said.
Many leaders of the movement, though, publicly embrace Trump to greater or lesser extent. Mancini said she thinks the marchers, most of them young because of the prevalence of school groups in attendance, telegraphed a message of support to the president. "For Trump, hopefully, he feels thanked and strengthened for his perspective," she said.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)