For the third time in a week, tens of thousands of people will flood the National Mall.
The 44th annual March for Life will be held Friday.
The president of the anti-abortion group, Jeanne Mancini, said many participants are feeling energized by President Donald Trump's inauguration and the Women's March on Washington the following day.
"We've seen an increasingly palpable enthusiasm this year, I think in large part because of some of the demonstrations that have occurred over the course of the last week. And then also, just with a hopeful outlook in terms of the couple of years ahead," she said.
The March for Life president said Thursday morning on News4 that a "special, unannounced guest" would attend the rally Friday morning. The group later announced that Vice President Mike Pence would speak at the rally.
Mancini said she expected some women would attend the March for Life for the first time after they saw the Women's March last week. Organizers of that march stated a pro-abortion rights platform.
"What we've seen is a frustration at the level of, many women have never participated in the march, but they want their voice heard too," she said.
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The group received a permit from the National Park Service to host an estimated 50,000 people.
Mancini said Thursday that they're expecting a crowd "in the tens of thousands, if not more."
The event is set to begin at 11:45 a.m. Friday with music, a rally and then a march. The rally will begin on the grounds of the Washington Monument. Then, participants will march along Constitution Avenue to Capitol Hill and the Supreme Court.
Mancini told people who plan to attend to expect "airport-like security" because some speakers at the event are high-profile. Kellyanne Conway, an adviser to President Donald Trump, is scheduled to speak.
March for Life organizers and Park Service officials said they do not expect any violent protests, like D.C. saw on Inauguration Day. But Mancini said they are ready for anything.
"We've got an emergency plan in place," she said.
For full details on the March for Life, see the group's website.