Leftists and their media outlets have been all too eager to dismiss President Donald Trump’s charge that as many as 5 million illegal aliens voted in the 2016 presidential election, enough to easily swing the popular vote to Hillary Clinton.

Many of these pundits, backed by an army of so-called “fact-checkers,” would have you believe that the number of illegals who are registering to vote and voting is insignificant. Oh, there may be the occasional, misguided “undocumented worker” who inadvertently wanders into the election booth, they seem to suggest. But, surely, not enough to make any difference.

Anyone who thinks that needs to think again.

There are a total of 43 million noncitizens currently living within US borders. Of these, approximately 12 million are illegal aliens. Not only are there well-documented reasons to believe that many of them may be violating election integrity, the fact is, many on the left are more than happy to see them do so. A Rasmussen Reports poll last year found that 53 percent of the Democratic Party supports allowing illegal aliens to vote.

Part of the problem is that election laws in the United States are a complicated hodgepodge of federal, state, and local rules, regulations, and red tape. Generally speaking, it is illegal for any noncitizens to cast a vote in any election, and those who do are at least theoretically subject to criminal penalties if they are caught.

But many states do not have a voter ID requirement. Worse yet, many states do not even have a requirement to certify citizenship, other than saying out loud that you are a citizen. All too many of the systems that are in place to prevent unlawful voting are either nonexistent or are so weak that they are useless. We are naïve to think that the millions of people who are present in the United States illegally are all resisting the temptation to cast unlawful votes, especially when so much is at stake – including their being able to continue illegally residing within our borders.

As I point out in my book, Clean House, in 2014, a disturbing study by political scientists at Old Dominion found that 6.4 percent of foreign nationals residing in the United States voted in the 2008 presidential election. If the key Old Dominion study results on the 2008 election were applied to 2016 — 1.41 million aliens may have voted illegally, with probably 1.13 million voting for Democrats.

Add to that the 2012 Pew Research Center study noting that “approximately 2.75 million people have active registrations in more than one state.” On top of that, the study revealed, more than “1.8 million deceased individuals are listed as active voters.” Combine those figures with the number of aliens the Old Dominion study cites, and the Trump allegations may not be so far out of line.

A full-scale, non-partisan federal voter fraud investigation is long overdue. I’m not aware of any systematic federal investigation of voter fraud – ever. Initially, such an investigation would be a simple matter of analyzing voter registration databases against federal databases of aliens and deceased individuals. Judicial Watch’s Election Integrity team, headed up by Robert Popper, former Deputy Chief of the Voting Section in the Civil Rights Division of the Department of Justice, would be more than happy to help.

Tom Fitton is president of Judicial Watch, a conservative foundation that promotes transparency, accountability and integrity in government, politics and the law.