Washington CNN  — 

Reeling after a weekend campaign rally with lower-than-expected turnout, President Donald Trump changed the subject Monday morning with a series of widely debunked lies about alleged voter fraud in US elections, stoking fears of a “rigged election” this November.

Trump tweeted an article highlighting Attorney General William Barr’s recent comment that expanding mail-in voting “absolutely opens the floodgates to fraud.” (This specific claim has been debunked many times.) Trump added his own commentary to the article, tweeting, “This will be the Election disaster of our time. Mail-In Ballots will lead to a RIGGED ELECTION!”

Trump then tweeted an all-caps missive with many of the debunked claims he’s been pushing all year: “RIGGED 2020 ELECTION: MILLIONS OF MAIL-IN BALLOTS WILL BE PRINTED BY FOREIGN COUNTRIES, AND OTHERS. IT WILL BE THE SCANDAL OF OUR TIMES!”

In a third tweet Monday morning, Trump said “Because of MAIL-IN BALLOTS, 2020 will be the most RIGGED Election in our nations history - unless this stupidity is ended,” and accused his political opponents of “using Covid in order to cheat by using Mail-Ins,” without providing proof.

Facts First: Trump is lying about voter fraud. CNN has repeatedly debunked these comments, and his primary allegation – that voting-by-mail leads to “massive fraud” – is completely untrue. As the coronavirus spread, bipartisan officials across the country expanded postal voting as a pandemic-safe option. This was endorsed by the Centers for Disease Control and Prevention.

Nonpartisan election experts rejected Trump’s claims on Monday within minutes of his tweets.

“That info is FALSE,” David Becker, founder of the nonpartisan Center for Election Innovation and research, tweeted in response to Trump’s posts Monday morning. “There is zero evidence to support it, and states have many protections in place to prevent rigging of mail ballots.”

It would be a “waste of paper” for foreign countries to print fraudulent ballots, tweeted Michael McDonald, a political science professor at the University of Florida who runs the United States Elections Project and is a leading authority on voting data and statistics. “The legally valid (ballots) printed by election officials have many safeguards to protect against fraudulent voting.”

In fact, contrary to Trump’s claims, there are many more cases of eligible voters who didn’t receive their mail ballots on time, and therefore potentially being disenfranchised, than there are examples of people fraudulently casting multiple ballots, according to a CNN review of data from a half-dozen recent primaries. Officials are trying to resolve these issues before November.

A Twitter spokesperson said Monday that the company reviewed Trump’s three tweets and determined they did not violate the company’s rules, even though they flagged Trump’s similar posts last month. Twitter pointed to its “civic integrity policy,” which says Twitter won’t take action on “broad, non-specific statements about the integrity of elections or civic processes.”

The same claims about “rigged elections” were posted to the President’s account on Facebook on Monday. Facebook did not respond to CNN’s request for comment on Monday morning.

This new line from Trump – that foreign countries might hijack mail-in voting to meddle in the US election – puts him in a contorted position. Trump and senior members of his 2016 campaign welcomed Russian interference in that election, according to special counsel Robert Mueller. And since taking office, Trump has not spoken out forcefully against foreign meddling, until now.

The Office of the Director of National Intelligence, which plays a leading role in identifying and countering foreign election security threats, declined to address Trump’s claim that foreign governments will “print millions” of mail-in ballots in the upcoming election. An official from the intelligence office referred questions about these unfounded claims back to the White House.

Trump’s claims on Monday were part of a larger effort to tarnish the legitimacy of mail-in voting, which the President claims will help only Democrats, even though nonpartisan researchers consistently say it doesn’t provide any major partisan advantage. As Trump slips in the polls against presumptive Democratic nominee Joe Biden, he has ramped up his criticism of postal voting.

Since the pandemic emerged earlier this year, numerous public polls have indicated that a large majority of Americans support expanding access to mail-in voting for the November election. A Quinnipiac University poll released last week found that 59% of American voters believe that all eligible voters in the US should be allowed to vote by mail, while only 38% opposed the idea.

Here’s a breakdown of CNN’s past fact-checks on mail-in voting and US elections.

This story has been updated to include a request for comment from the Office of the Director of National Intelligence, as well as a comment from a Twitter spokesperson that Trump’s tweets did not violate the company’s “civic integrity policy.”

CNN’s Donie O’Sullivan and Zachary Cohen contributed to this report