U.S. Vice President Mike Pence fired up tens of thousands of anti-abortion activists who gathered on Friday for the 44th March for Life, celebrating a political shift in their favor with the election of President Donald Trump.

"Life is winning again in America," Pence told the demonstrators on the National Mall, near where Trump was sworn in a week ago before hundreds of thousands.

The March for Life took place in the same area where even more massive crowds flooded Washington a day after Trump's inauguration in favor of women's rights, including abortion rights.

Pence, a longtime hero of the anti-abortion movement, is the most senior government official to speak in person at the rally, organizers said. As governor of Indiana, he signed what were seen as some of the nation's strictest abortion laws.

Pence praised "the election of pro-life majorities in the Congress of the United States of America," Trump's upcoming nomination of an anti-abortion Supreme Court justice, and the president's reinstatement on Monday of a policy that cuts off U.S. funding to healthcare providers that promote or provide abortions overseas.

"It's the best day I've ever seen for the March of Life," he said.

Trump senior aide Kellyanne Conway was one of many women to address the demonstrators before they started their march from the Mall to the U.S. Supreme Court, about 1.5 miles (2 km) away.

"We hear you. We see you. We respect you," Conway said. "And we look forward to working with you."

Protesters hoisted signs saying "Choose life," "I am the pro-life generation," and "Equal Rights For Unborn People."

A Christian rock band warmed up the crowd for Pence, leading people in hand-clapping at the rally within sight of the White House.

"We're here to stand up for the unborn because no one else can, and having Donald Trump in the White House makes everyone more enthusiastic," said Jim Kolar, 59, of West Palm Beach, Florida.

Organizers had no immediate estimate of crowd size, but the march to the Supreme Court after the rally filled the street for many blocks amid chants of "We love babies, yes, we do, we love babies, how 'bout you?"

"This is good, this is a good turnout," said the Rev. Kevin Cusick, a Catholic priest from Benedict, Maryland, who has been coming to the marches off and on for more than 40 years.

The March for Life is held each year close to the anniversary of the court's Roe v. Wade ruling that legalized abortion in 1973.

Trump has said Roe v. Wade should be overturned and has vowed to appoint an anti-abortion justice to fill the Supreme Court seat left vacant by the death of Justice Antonin Scalia last year.

He also has pledged to defund Planned Parenthood, which draws the ire of many Republicans because it provides abortions, along with other services.

Abortion rights supporters say cutting off funding for abortion providers will prevent poor women from getting other critical heath care and birth control that could prevent unwanted pregnancies.

The rally comes as the number of U.S. abortions has fallen to a record low. The Guttmacher Institute, a reproductive health and rights organization, said last week that it dropped below 1 million in 2013 for the first time since 1975.

A Quinnipiac University poll released on Friday showed that 64 percent of Americans say abortion should be legal in all or most cases, while 31 percent said it should be illegal in all or most cases.

Anti-abortion forces are often inspired by a religious conviction that life begins at conception and see abortion as murder.