Donald Trump, with an eye towards his re-election campaign, reminded a key part of his conservative political base of all he has done to chip away at abortion rights since becoming president.

"Since my first day in office, I've taken historic action to support America's families and to protect the unborn," he said at the March for Life rally on the National Mall, becoming the first US president to address the event in person. "When we see the image of the baby in the womb, we glimpse the majesty of God's creation."

He walked the anti-abortion crowd through the actions he has taken since January 2017, reminding them "we issued a landmark pro-life rule to govern the use of Title X taxpayer funding."

Mr Trump also portrayed himself as fighting Democrats in Congress who want to change laws to make it easier for women to end pregnancies.

"I notified Congress that I would veto any legislation that weakens pro-life policies or that encourages the destruction of human life," he said to loud cheers. "As the Bible teaches us, each person is wonderfully made."

Protests across US after abortion laws enforced Show all 20 1 /20 Protests across US after abortion laws enforced Protests across US after abortion laws enforced Missouri Thousands of demonstrators march in support of Planned Parenthood and pro-choice as they protest a state decision that would effectively halt abortions by revoking the license of the last center in the state that performs the procedure, during a rally in St. Louis, Missouri, May 30, 2019. (Photo by SAUL LOEB / AFP) (Photo credit should read SAUL LOEB/AFP/Getty Images) SAUL LOEB AFP/Getty Protests across US after abortion laws enforced Alabama MONTGOMERY, AL - MAY 19: Lindsey Shelton participates in a rally against one of the nation's most restrictive bans on abortions on May 19, 2019 in Montgomery, Alabama. Demonstrators gathered to protest HB 314, a bill passed by the Alabama Legislature last week making almost all abortion procedures illegal. (Photo by Julie Bennett/Getty Images) Julie Bennett Getty Protests across US after abortion laws enforced New York Alison Hickerson from New York City poses for a photo as she take part in a rally in front of the Middle Collegiate Church in the East Village of New York May 21, 2019. - Demonstrations were planned across the US on Tuesday in defense of abortion rights, which activists see as increasingly under attack. The "Day of Action" rallies come after the state of Alabama passed the country's most restrictive abortion ban, prohibiting the procedure in all cases, even rape and incest, unless the mother's life is at risk. Alabama is among about 14 states which have adopted laws banning or drastically restricting access to abortion, according to activists. (Photo by TIMOTHY A. CLARY / AFP) (Photo credit should read TIMOTHY A. CLARY/AFP/Getty Images) TIMOTHY A. CLARY AFP/Getty Protests across US after abortion laws enforced Georgia ATLANTA, GA - MAY 21: Melissa Simpson holds up her arm with "My Body My Choice" written on it during a protest against recently passed abortion ban bills at the Georgia State Capitol building, on May 21, 2019 in Atlanta, United States. The bill would ban abortion when a fetal heartbeat is detected. The Alabama abortion law, signed by Gov. Kay Ivey last week, includes no exceptions for cases of rape and incest, outlawing all abortions except when necessary to prevent serious health problems for the woman. Though women are exempt from criminal and civil liability, the new law punishes doctors for performing an abortion, making the procedure a Class A felony punishable by up to 99 years in prison. (Photo by Elijah Nouvelage/Getty Images) Elijah Nouvelage Getty Protests across US after abortion laws enforced Atlanta ATLANTA, GA - MAY 21: Women hold signs during a protest against recently passed abortion ban bills at the Georgia State Capitol building, on May 21, 2019 in Atlanta, Georgia. The Georgia "heartbeat" bill would ban abortion when a fetal heartbeat is detected. The Alabama abortion law, signed by Gov. Kay Ivey last week, includes no exceptions for cases of rape and incest, outlawing all abortions except when necessary to prevent serious health problems for the woman. Though women are exempt from criminal and civil liability, the new law punishes doctors for performing an abortion, making the procedure a Class A felony punishable by up to 99 years in prison (Photo by Elijah Nouvelage/Getty Images) Elijah Nouvelage Getty Protests across US after abortion laws enforced Alabama Pro-Choice protesters march through the streets of Birmingham, Alabama, during the March For Reproductive Freedom on May 19, 2019. - The state of Alabama passed a near-total abortian ban on May 14, 2019, one of the nation's most restrictive bans on abortions in decades. (Photo by Seth HERALD / AFP) (Photo credit should read SETH HERALD/AFP/Getty Images) SETH HERALD AFP/Getty Protests across US after abortion laws enforced Missouri ST LOUIS, MO - MAY 31: Pro-Choice supporters, along with Planned Parenthood staff celebrate and rally outside the Planned Parenthood Reproductive Health Services Center on May 31, 2019 in St Louis, Missouri. A judge has issued an order allowing Missouri's only abortion clinic to continue providing the service and maintaining their license until June 4. (Photo by Michael Thomas/Getty Images) Michael Thomas Getty Protests across US after abortion laws enforced Alabama Pro-Choice protesters march through the streets of Birmingham, Alabama, during the March For Reproductive Freedom on May 19, 2019. - The state of Alabama passed a near-total abortian ban on May 14, 2019, one of the nation's most restrictive bans on abortions in decades. (Photo by Seth HERALD / AFP) (Photo credit should read SETH HERALD/AFP/Getty Images) SETH HERALD AFP/Getty Protests across US after abortion laws enforced Georgia ATLANTA, GA - MAY 21: People hold signs during a protest against recently passed abortion ban bills at the Georgia State Capitol building, on May 21, 2019 in Atlanta, Georgia. The Georgia "heartbeat" bill would ban abortion when a fetal heartbeat is detected. The Alabama abortion law, signed by Gov. Kay Ivey last week, includes no exceptions for cases of rape and incest, outlawing all abortions except when necessary to prevent serious health problems for the woman. Though women are exempt from criminal and civil liability, the new law punishes doctors for performing an abortion, making the procedure a Class A felony punishable by up to 99 years in prison (Photo by Elijah Nouvelage/Getty Images) Elijah Nouvelage Getty Protests across US after abortion laws enforced Georgia ATLANTA, GA - MAY 21: Melissa Simpson snaps her fingers in support of a speaker during a protest against recently passed abortion ban bills at the Georgia State Capitol building, on May 21, 2019 in Atlanta, Georgia. The Georgia "heartbeat" bill would ban abortion when a fetal heartbeat is detected. The Alabama abortion law, signed by Gov. Kay Ivey last week, includes no exceptions for cases of rape and incest, outlawing all abortions except when necessary to prevent serious health problems for the woman. Though women are exempt from criminal and civil liability, the new law punishes doctors for performing an abortion, making the procedure a Class A felony punishable by up to 99 years in prison (Photo by Elijah Nouvelage/Getty Images) Elijah Nouvelage Getty Protests across US after abortion laws enforced Missouri Thousands of demonstrators march in support of Planned Parenthood and pro-choice as they protest a state decision that would effectively halt abortions by revoking the license of the last center in the state that performs the procedure, during a rally in St. Louis, Missouri, May 30, 2019. (Photo by SAUL LOEB / AFP) (Photo credit should read SAUL LOEB/AFP/Getty Images) SAUL LOEB AFP/Getty Protests across US after abortion laws enforced Washington, DC WASHINGTON, DC - MAY 23: People wait for the start of a news conference regarding womenâ€™s health care, on Capitol Hill May 23, 2019 in Washington, DC. The news conference was held to discuss the reintroduction of the "Women's Health Protection Act " and address the state-based attacks on abortion rights. (Photo by Mark Wilson/Getty Images) Mark Wilson Getty Protests across US after abortion laws enforced Louisiana Handsmaid themed protesters stand outside Jackson Square in the French Quarter of New Orleans, Louisiana, on May 25, 2019, to protest the proposed Heartbeat Bill that will ban abortion after 6 weeks in that state, scheduled for a vote on May 28. (Photo by Emily KASK / AFP) (Photo credit should read EMILY KASK/AFP/Getty Images) EMILY KASK AFP/Getty Protests across US after abortion laws enforced Louisiana Handsmaid themed protesters march down Bourbon Street in the French Quarter of New Orleans, Louisiana, on May 25, 2019, to protest the proposed Heartbeat Bill that will ban abortion after 6 weeks in that state scheduled for a vote on May 28. (Photo by Emily KASK / AFP) (Photo credit should read EMILY KASK/AFP/Getty Images) EMILY KASK AFP/Getty Protests across US after abortion laws enforced Missouri Thousands of demonstrators march in support of Planned Parenthood and pro-choice as they protest a state decision that would effectively halt abortions by revoking the license of the last center in the state that performs the procedure, during a rally in St. Louis, Missouri, May 30, 2019. (Photo by SAUL LOEB / AFP) (Photo credit should read SAUL LOEB/AFP/Getty Images) SAUL LOEB AFP/Getty Protests across US after abortion laws enforced Missouri TOPSHOT - Thousands of demonstrators march in support of Planned Parenthood and pro-choice as they protest a state decision that would effectively halt abortions by revoking the license of the last center in the state that performs the procedure, during a rally in St. Louis, Missouri, May 30, 2019. (Photo by SAUL LOEB / AFP) (Photo credit should read SAUL LOEB/AFP/Getty Images) SAUL LOEB AFP/Getty Protests across US after abortion laws enforced Missouri Pro-choice supporters and staff of Planned Parenthood hold a rally outside the Planned Parenthood Reproductive Health Services Center in St. Louis, Missouri, May 31, 2019, the last location in the state performing abortions, after a US Court announced the clinic could continue operating. - A US Court on May 31, 2019 blocked Missouri from closing the clinic. (Photo by SAUL LOEB / AFP) (Photo credit should read SAUL LOEB/AFP/Getty Images) SAUL LOEB AFP/Getty Protests across US after abortion laws enforced Washington, DC Abortion rights activists rally in front of the US Supreme Court in Washington, DC, on May 21, 2019. - Demonstrations were planned across the US on Tuesday in defense of abortion rights, which activists see as increasingly under attack. The "Day of Action" rallies come after the state of Alabama passed the country's most restrictive abortion ban, prohibiting the procedure in all cases, even rape and incest, unless the mother's life is at risk. Alabama is among about 14 states which have adopted laws banning or drastically restricting access to abortion, according to activists. (Photo by Andrew CABALLERO-REYNOLDS / AFP) (Photo credit should read ANDREW CABALLERO-REYNOLDS/AFP/Getty Images) ANDREW CABALLERO-REYNOLDS AFP/Getty Protests across US after abortion laws enforced Georgia ATLANTA, GA - MAY 21: Heather Masson, left, and Victoria Jernigan hold signs promoting a woman's right to choose during a protest against recently passed abortion ban bills at the Georgia State Capitol building, on May 21, 2019 in Atlanta, Georgia. The bill would ban abortion when a fetal heartbeat is detected. The Alabama abortion law, signed by Gov. Kay Ivey last week, includes no exceptions for cases of rape and incest, outlawing all abortions except when necessary to prevent serious health problems for the woman. Though women are exempt from criminal and civil liability, the new law punishes doctors for performing an abortion, making the procedure a Class A felony punishable by up to 99 years in prison (Photo by Elijah Nouvelage/Getty Images) Elijah Nouvelage Getty Protests across US after abortion laws enforced Alabama Cristina Castor (L) and Julian Kersh pose for a portrait in Ingram Park in Birmingham, Alabama, May 19, 2019 during the March for Reproductive Freedom. - "If this goes all the way and flips Roe v Wade at that point it just seems like where is this going to stop," Kersh said. The state of Alabama passed a near-total abortion ban on May 14, 2019 making it the most restrictive law in the United States. (Photo by Seth HERALD / AFP) (Photo credit should read SETH HERALD/AFP/Getty Images) SETH HERALD AFP/Getty

Trump rarely speaks about his own faith, but he invoked a higher power several times on Friday.

"We've taken decisive action, religious liberty - so important, religious liberty," he said. "Very strongly attacked in our nation. You see it better than anyone. But we are stopping it.

"Sadly, the far left is actively working to erase our God-given rights, shut down faith-based charities, ban religious believers from the public square and silence Americans who believe in the sanctity of life," Mr Trump said.

He even contended House Democrats impeached him and are arguing for the Senate to remove him because he is pushing a conservative agenda. "They are coming after me because I am fighting for you. ... We will win because we know how to win," he said at the March for Life on the National Mall.

Notably, he also reminded the large audience that he put two conservative justices on the Supreme Court, Neil Gorsuch and Brett Kavanaugh - both are staunchly pro-life. And conservative voters say they think about Supreme Court vacancies more than liberal voters do, according to reams of polling data.

The United States has "never had a stronger defender in the White House," he said, hammering home his point.

The event was an official White House policy affair, but his brief time on the Mall felt more like one of his campaign rallies.

He came out to Lee Greenwood's "God Bless the USA," which is his rally introduction song. He left to the Rolling Stones' "You Can't Always Get What You Want."

The president, always thinking about his re-election bid, became the first chief executive to address the march in person. In doing so, he excited part of his conservative political base months before an election that political strategists say likely will come down to which side can get their base to the voting booth in big numbers.

New polling conducted this month by the nonpartisan Gallup organisation shows that bloc's views on the subject remain largely unchanged. But Gallup found overall disatisfaction with abortion laws now stands at 58 percent, the highest figure since it began asking voters in 2002. Democratic and independent voters want less strict abortion laws, but Mr Trump has shown little interest in expanding his political base, again and again trying to please conservatives.

Mr Trump has fully endorsed the pro-life movement after anti-abortion groups and activists worried as he took office that he might not live up to promises he made them as a candidate in 2016.

But he was greeted warmly when he arrived on the National Mall on Friday afternoon.

That's because he has endorsed the kind of abortion ban favoured by the pro-life movement. (He has said he supports exceptions for rape and incest cases, as well as when the life of a mother is at risk.) Mr Trump also frequently mentions at political rallies and some official White House events that he supports banning abortions after the 20th week of pregnancy.

As he did Friday, Mr Trump is never shy when reminding a specific group that he has kept his campaign promises.

"When I ran for office, I pledged to stand for life. And as President, that's exactly what I've done. And I have kept my promise, and I think everybody here understands that fully," he told a pro-life group in May 2018.

But also fuelling America's fight over abortion are powerful groups that support a woman's right to choose to end a pregnancy.

One is NARAL Pro-Choice America says in a statement on its website that the president "has already shown his anti-woman agenda in his actions." The group also raised alarms about Mr Trump's "support for a number of anti-choice policies that would have a devastating impact on women nationwide."

But anti-abortion organisations and GOP lawmakers hailed him for being the first president to address the group in person, and for his policy actions.