Donald Trump on Saturday slammed civil rights activist Rep. John Lewis (D-Ga.) as "all talk, talk, talk -- no action or results," after the congressman's remark that Trump is not "a legitimate president."

Lewis, who has served in Congress since 1987, said Friday in an NBC News interview that he would not attend Trump's swearing-in on Inauguration Day.

"You cannot be at home with something that you feel that is wrong, is not right," he said. It will be the first swearing-in that the longtime congressman will miss.

Lewis told NBC that Trump is not a "legitimate president" because "the Russians participated in helping this man get elected, and they helped destroy the candidacy of Hillary Clinton."

Trump tweeted, "Congressman John Lewis should spend more time on fixing and helping his district, which is in horrible shape and falling apart (not to mention crime infested) rather than falsely complaining about the election results. All talk, talk, talk -- no action or results. Sad!"

Lewis rose to prominence in the 1960s for his role in the civil rights movement; he was one of the speakers at the 1963 March on Washington. He was beaten by police during a march he helped lead in 1965 in Selma, Alabama, drawing attention to hurdles for blacks to vote. Lewis protested alongside Dr. Martin Luther King, Jr. that day and on other occasions.