President Trump will deliver an in-person speech on Friday at the March for Life, an annual rally held in Washington protesting the legalization of abortion.

Trump will be the first president in history to appear at the march, one of the highest-profile events of the anti-abortion movement. March for Life is in its 47th year, having taken place every year since the passage of Roe v. Wade, the Supreme Court decision that legalized abortion nationwide.

Last year, Vice President Mike Pence made a surprise appearance at the march before roughly 100,000 attendees. The president also gave a message of support for the cause to attendees through a live video.

Jeanne Mancini, president of the organizing group, celebrated the announcement in a statement, saying Trump had been loyal to the anti-abortion movement.