President-elect Donald Trump fired off a series of tweets late Monday and early Tuesday criticizing CNN for reporting that his claims about voter fraud are baseless -- which they are.

Shortly after 9 p.m., Trump began retweeting supporters who had criticized CNN's Jeff Zeleny because he accurately reported that there was no evidence -- nor has the transition team provided any-- to support Trump's claim that millions of fraudulent votes had been cast for Hillary Clinton.

"[W]hat PROOF do u have DonaldTrump did not suffer from millions of FRAUD votes? Journalist? Do your job!" read the first post that Trump retweeted. "Just another generic CNN part time wannabe journalist!," read the second.

"@CNN still doesn't get it," Trump added. "They will never learn!"

One post Trump retweeted came from a Twitter user whose bio says he's 16, who, like the others, called Zeleny a "bad reporter" because he did not have evidence that Trump was not a victim of voter fraud, a double-negative reasoning used to defend many conspiracy theories.

Finally, Trump issued his own attack on CNN: ".@CNN is so embarrassed by their total (100%) support of Hillary Clinton, and yet her loss in a landslide, that they don't know what to do," he wrote.

He continued the attack in a tweet just after 6:30 a.m. Tuesday: "I thought that @CNN would get better after they failed so badly in their support of Hillary Clinton however, since election, they are worse!"

A CNN spokesperson declined to comment. Zeleny responded to Trump with a request for examples of the fraud.

"@realDonaldTrump Good evening! Have been looking for examples of voter fraud. Please send our way. Full-time journalist here still working," Zeleny wrote on Twitter.

Related: News media struggles to cover Trump's tweets and falsehoods

Trump's initial claim that Clinton's lead in the popular vote was a result of "millions of people who voted illegally" had been promoted on conspiracy theory sites like Infowars.com before Trump himself tweeted it on Sunday. The claim appears to have been first promoted by Gregg Phillips, a conservative activist with more than 26,000 Twitter followers.

Since Trump tweeted the conspiracy theory, CNN anchors and reporters have repeatedly stressed that there is no evidence to support the claim. Online, CNN's headline read, "Trump falsely claims 'millions of people who voted illegally' cost him popular vote."

Election officials in California and Virginia have also called Trump's claims "unsubstantiated" and "unfounded."

Related: Top journalists warn of threats to press freedom under Trump

Trump's penchant for peddling conspiracy theories and attacking critics and media organizations on Twitter is unprecedented, and has been cause for concern among journalists and media watchdogs who are wrestling with how to cover a president who is a leading source of misinformation.