PRESIDENT-elect Donald Trump started a US long holiday weekend that honours slain black civil rights leader Martin Luther King Jr by blasting another African-American activist and politician, who said he doesn't see Mr Trump as a "legitimate president”.
Democratic Representative John Lewis, of Georgia, had said on Friday he thought hacking by Russians had helped Mr Trump get elected in November.
Mr Lewis said he did not plan to attend Mr Trump's January 20 inauguration, the first time he would miss such an event since being elected to the House in 1986.
In reply Mr Trump tweeted that Mr Lewis was falsely complaining about election results and instead "should spend more time on fixing and helping his district, which is in horrible shape and falling apart (not to mention crime infested)”.
"All talk, talk, talk - no action or results. Sad!” Mr Trump tweeted.
He followed up on Saturday night with another tweet targeting the Georgia Democrat: "Congressman John Lewis should finally focus on the burning and crime infested inner-cities of the US. I can use all the help I can get!”
Mr Lewis was a leading figure in the 1960s civil rights movement.
He is the last surviving speaker from the 1963 March on Washington, led by Mr King.
"I believe in trying to work with people,” Mr Lewis said in the Friday interview.
"It's going to be very difficult. I don't see this president-elect as a legitimate president.”
Several of Mr Trump's fellow Republicans criticised his attack on Mr Lewis.
Senator Ben Sasse of Nebraska tweeted that "John Lewis and his 'talk' have changed the world”.
Neoconservative critic Bill Kristol tweeted "It's telling, I'm afraid, that Donald Trump treats (Russian President) Vladimir Putin with more respect than he does John Lewis”.
In another development, African-American Broadway star Jennifer Holliday, who has performed for Democrat and Republican presidents, pulled out of performing at the inauguration, apologising for her "lapse of judgment” in accepting the gig.
INM, THE AUSTRALIAN