President Biden plans to reach out to disaffected Black supporters on Monday by taking his campaign to the site of one of the most horrific hate crimes of recent years and decrying the racism and extremism that have shaped U.S. politics.

Mr. Biden will fly from Wilmington, Del., where he spent the weekend at his family home, to Charleston, S.C., to address parishioners and other guests at Emanuel African Methodist Episcopal Church, where a white supremacist gunman killed the pastor and eight others in 2015.

The visit will be the second part of the president’s two-stage opening campaign swing of the election year after a speech near Valley Forge, Pa., on Friday. There he condemned his likely Republican opponent, former President Donald J. Trump, on the eve of the third anniversary of the Jan. 6, 2021, attack on the Capitol. By appearing at Mother Emanuel, as the church is known, the president hopes to remind a key voting bloc of the significance of the November election.

In a statement on Sunday, the Biden campaign called the church “a venue that embodies the stakes for the nation at this moment.” After the massacre in 2015, Mr. Biden, then the vice president, joined President Barack Obama in Charleston at the funeral of the pastor, the Rev. Clementa Pinckney, a state senator, where Mr. Obama delivered a eulogy and sang “Amazing Grace.” Mr. Biden, then mourning his son Beau, who had died of cancer weeks earlier, returned a couple days later to pray with the congregation at the church.

Mr. Biden has often attributed his decision to run for president in 2020 to Mr. Trump’s racial provocations, particularly when Mr. Trump said there were “very fine people on both sides” of a white supremacist rally in Charlottesville, Va., in 2017. But Mr. Biden has lost support among Black supporters who could be critical to his hopes for beating Mr. Trump in a rematch this year.

Twenty-two percent of Black voters in six battleground states told pollsters from The New York Times and Siena College last fall that they would vote for Mr. Trump, while the president was drawing 71 percent. Such support indicates a surge for Mr. Trump, who won 6 percent of Black voters nationally in 2016 and 8 percent in 2020.

Black Democrats in South Carolina helped save Mr. Biden’s flagging campaign for the party’s nomination in 2020 after weak showings in Iowa and New Hampshire. The president has since orchestrated South Carolina’s ascendance as the first primary state for 2024. To shore up support, Democrats have flooded the state in recent weeks with money, staff and surrogates before the Feb. 3 primary.

After his appearance in Charleston on Monday, Mr. Biden is scheduled to fly to Dallas for a wake for former Representative Eddie Bernice Johnson, a pioneering Black member of Congress for three decades who died at 89 last week.