President Joe Biden on Tuesday condemned the poison of white supremacy and said the nation must "reject the lie" of the racist "replacement theory" espoused by the shooter who murdered 10 black Americans in Buffalo.

Watch Biden's remarks in the player above.

Speaking to victims' families, local officials and first responders, Biden said America's diversity is its strength and the nation must not be be distorted by a "hateful minority."

WATCH: Buffalo mourns as details emerge about gunman's plans for second attack

"In America, evil will not win, I promise you," Biden said. "Hate will not prevail, white supremacy will not have the last word."

Biden spoke after he and first lady Jill Biden paid their respects Tuesday at a makeshift memorial of blossoms, candles and messages of condolence outside the Tops supermarket, where on Saturday a young man armed with an assault rifle targeted Black people in the deadliest racist attack in the U.S. since Biden took office.

In Buffalo, the president was confronting anew the forces of hatred he frequently says called him back to seek the White House.

"Jill and I have come to stand with you, and to the families, we have come to grieve with you," Biden said. He added: "Now's the time for people of all races, from every background, to speak up as a majority and American and reject white supremacy."

Replacement theory can be described as a racist ideology, which has moved from white nationalist circles to mainstream, that says white people and their influence are being intentionally "replaced" by people of color.

READ MORE: What is 'great replacement theory' and how does it fuel racist violence?

Biden's condemnation of white supremacy is a message he has delivered several times since he became the first president to specifically address white supremacy in an inaugural speech, calling it "domestic terrorism that we must confront." However, such beliefs remain an entrenched threat at a time when his administration has been focused on addressing the pandemic, inflation and the war in Ukraine.