President-elect Donald Trump went head-to-head on Twitter with CNN anchor Jeff Zeleny over Trump's unfounded claims that "millions" of illegal votes were cast in the 2016 election.

Zeleny referred to Trump as a "sore winner" in an on-air report Monday night after the president-elect failed to provide any evidence of the rampant voter fraud he asserted.

In response, Trump promoted a series of tweets from his supporters attacking Zeleny, including one that called the newsman a "part time wannabe journalist."

Zeleny fired back at Trump on Twitter, challenging him to provide proof of his voter-fraud claims: "@realDonaldTrump Good evening! Have been looking for examples of voter fraud. Please send our way. Full-time journalist here still working."

The argument stems from a missive Trump tweeted Sunday without any evidence to back it up: "In addition to winning the Electoral College in a landslide, I won the popular vote if you deduct the millions of people who voted illegally."

Trump's Twitter followers leaned in on Zeleny, and he promoted several of their tweets:

Trump tweeted again on Tuesday morning:

Top election officials in states where Trump alleged voter fraud have rebuked his assertions, calling them "unsubstantiated."

The president-elect previously stoked claims of voter fraud in the weeks leading up to the presidential election, urging his supporters to be watchful of irregularities at the polls.

Before the election, Trump and his surrogates openly predicted that it would be "rigged."

Trump's latest allegations of fraud followed news that Wisconsin officials were preparing a vote recount that was requested by Green Party nominee Jill Stein.

Though Trump defeated Democrat Hillary Clinton in the Electoral College 306 to 232, securing the presidency, he trails by more than 2 million votes with counting still incomplete.

Clinton's campaign had said it would participate in the recount initiated by Stein despite having found no "actionable evidence" of impropriety in the polling.