Fact-Checking Trump's Claims About 'Serious Voter Fraud'

— -- Donald Trump made a controversial claim on Twitter Sunday -- amid a push for recounts in several states -- that "millions of people" voted illegally and that "serious voter fraud" occurred in California, New Hampshire and Virginia.

The president-elect didn't cite any evidence, but transition team spokesman Jason Miller said today that two studies from recent years appeared to validate his claim.

ABC News has fact-checked Trump’s claims and found them to be false.

Trump Claim: “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”

Our Grade: False

Explanation: Trump offered no proof to back up this claim, and ABC News, which monitored all 50 states for voting irregularities on election night, has found no evidence of widespread voter fraud.

Miller today cited a Pew Charitable Trust study from 2012, which found that approximately 24 million voter registrations were invalid or significantly inaccurate, more than 1.8 million deceased individuals were listed as voters, and approximately 2.75 million people had registrations in more than one state.

But David Becker, the study’s primary author, tweeted today that they found “no evidence that voter fraud resulted” from the “millions of out of date registration records due to people moving or dying.” Becker also tweeted that voter lists are much more accurate today than in 2012 because of new data-sharing programs.

The existence of millions of voter registration errors does not mean that fraudulent votes were actually cast, according to numerous election experts.

Miller also cited a highly controversial 2014 study by Old Dominion University professors Jesse Richman and David Earnest which claimed -- based on data from an online survey -- that 14 percent of non-citizens in both the 2008 and 2010 elections indicated they were registered to vote, and that it was "possible" that enough non-citizens in North Carolina voted to affect Obama’s 2008 win in that state. The study’s methodology has been widely criticized.

Richman, the lead author, told ABC News that his findings have been “taken out of context” and should not be used “to make an unsupported claim concerning massive vote fraud.”

Trump Claim: “Serious voter fraud in Virginia, New Hampshire and California - so why isn't the media reporting on this? Serious bias - big problem!”

Our Grade: False

Explanation: Trump offered no proof to back up this claim, and ABC News found no evidence of widespread voter fraud in those states.

California Secretary of State Alex Padilla called Trump’s allegations “unsubstantiated” and “absurd” and said in a statement Sunday that “his reckless tweets are inappropriate and unbecoming of a President-elect."

Similarly, Virginia Commissioner of Elections Edgardo Cortés called the claims of voter fraud “unfounded.” “Virginia's election was well administered by our 133 professional local registrars, with help from hundreds of election officials and volunteers who worked to guarantee a good experience for eligible Virginia voters. The election was fair and all votes cast by eligible voters were accurately counted,” Cortés said in a statement Monday.

And Dave Scanlan, a spokesman for the New Hampshire Secretary of State’s office, said they “have never been presented with any evidence that supports” Trump’s claim of serious voter fraud, noting that they only heard of a “handful” of voting issues this year.

The Lawyers’ Committee for Civil Rights Under Law -- which led Election Protection, the nation’s largest non-partisan voter protection program -- called Trump’s fraud claims “bombastic” and “contrary to the evidence amassed this election cycle,” indicating that voter suppression was the bigger problem.

Weeks before Election Day, election officials in all 50 states told ABC News that their states' election processes were sound and could not be “rigged.” Kay Stimson, spokeswoman for the National Association of Secretaries of State, said on Sunday that she disagreed with Trump’s voter fraud claims and had “no information that can help to explain what sources or information are behind the basis of [Trump’s] tweets.”