Rep. John Lewis (D-Ga.) on Tuesday endorsed launching impeachment proceedings against President Trump while speaking on the floor of the House.

"The future of our democracy is at stake. I truly believe the time to begin impeachment proceedings against this president has come. To do otherwise would betray the foundations of our democracy."

Why it matters: Lewis is a civil rights icon who has been called "the conscience of the House." He was one of the most influential members to resist endorsing impeachment, and his announcement on Tuesday is likely to open the floodgates for members of the Congressional Black Caucus and other holdouts.

After finishing his speech, Lewis reportedly told Politico's Andrew Desiderio that Speaker Nancy Pelosi was aware that his announcement was coming. Pelosi is holding a Democratic caucus meeting on the topic of impeachment later on Tuesday.

Go deeper: Momentum builds among Dems for Trump impeachment