President-elect Donald Trump harshly responded to civil rights icon and Georgia Rep. John Lewis on Saturday, calling him “all talk” and “no action” after Lewis said Trump was not a “legitimate” president.

“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,” Trump tweeted Saturday, which happened to fall on the weekend of the Martin Luther King Jr. federal holiday.

Lewis — an ally of King who was brutally beaten by police in Selma, Alabama, in 1965 while marching for civil rights — represents a Georgia district that includes most of Atlanta. On the campaign trail, Trump regularly decried crime in urban areas while pledging to revitalize neighborhoods primarily populated by black Americans.

A Hillary Clinton supporter, Lewis criticized Trump’s ascension to head of state due to Russia’s alleged meddling in the 2016 election.

“I don’t see this President-elect as a legitimate president,” the long-serving Democrat told NBC News’ Chuck Todd in a clip released Friday.

It was an astonishing rebuke by a sitting member of Congress toward an incoming President. Trump, however, largely launched his political career by calling into question the legitimacy of President Barack Obama’s presidency by repeatedly suggesting he wasn’t born in the United States.

Democrats, highlighting Lewis’ contributions to the civil rights movement, swiftly condemned Trump Saturday morning.

“Ahead of #MLKday2017, let us remember that many have tried to silence @repjohnlewis over the years. All have failed,” tweeted House Minority Leader Nancy Pelosi.

California Sen. Kamala Harris said Lewis doesn’t deserve to be attacked by Trump.

“John Lewis is an icon of the Civil Rights Movement who is fearless in the pursuit of justice and equality. He deserves better than this,” she tweeted.

Republican Sen. Ben Sasse, a frequent Trump critic, praised Lewis, “John Lewis and his ‘talk’ have changed the world.”

Rep. Keith Ellison, who is vying to become the Democratic National Committee chairman, said Trump has “no clue” who Lewis is.

“.@repjohnlewis knows true sacrifice. @realDonaldTrump has no clue. When cluelessness collides with power oppression results. Resistance,” the Minnesota lawmaker said.

Lewis is one of an increasing number of Democratic lawmakers who are boycotting Trump’s inauguration after learning more about Russia’s role in the 2016 election. Intelligence agencies have said Russia hacked Democratic groups with the intent of hurting Clinton’s campaign and aiding Trump’s. The President-elect has repeatedly expressed skepticism at the conclusions.

“You cannot be at home with something that you feel that is wrong,” Lewis told NBC News.

California Rep. Barbara Lee said earlier this week she will spend the day organizing.

“Donald Trump has proven that his administration will normalize the most extreme fringes of the Republican Party. On Inauguration Day, I will not be celebrating. I will be organizing and preparing for resistance,” she said Thursday in a statement.

Reps. Luis Gutierrez of Illinois, Jared Huffman of California and Katherine Clark of Massachusetts, are also boycotting the historic event.

“I cannot go to (the) inauguration of a man who’s going to appoint people to the Supreme Court and turn back the clock on women and turn back the clock on immigrants and the safety and freedom that we fought for them,” Gutierrez said last month on CNN’s “New Day.”