One of the leading election fraud experts says there is virtually no way to determine how many fraudulent votes were cast in 2016, but he is applauding President Trump's call for an investigation, saying the U.S. is long overdue in taking important steps to ensure more accurate elections.

Trump has said repeatedly that he believes the votes of illegal aliens across the United States are responsible for Hillary Clinton winning the popular vote. The issue flared again, both at a White House press briefing and in a pair of Trump tweets that announce his call for a formal probe.

Former Federal Elections Commission member Hans von Spakovsky now manages the Election Law Reform Initiative at the Heritage Foundation. While not weighing on Trump's specific assertions, Von Spakovsky told WND and Radio America a thorough federal investigation into voting laws is clearly warranted.

"I think it's long overdue," he said. "There's never been any systematic, organized effort by the federal government to try to improve and check on the election integrity of the United States. I think this is a great idea."

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He said Trump's call is a radical departure from the Obama administration's position.

"It's a complete turnaround from the Obama administration, which for the past eight years has done everything it can to try to stop improvements in election integrity: things like Voter ID, things like verifying the citizenship of people who are registered to vote," von Spakovsky said. "The Obama administration has tried to stop that and has minimized or basically said, 'There's no fraud to worry about anywhere.'"

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While the media point out that Trump has provided no evidence of his assertions that millions of illegal aliens cast ballots last year, von Spakovsky said the same press corps had no problem with President Obama's collision with the facts on this same issue earlier in the month.

"President Obama told a whopper of a lie in his last press release, when he said that when he got out of office he would continue to oppose voter ID and other efforts to try to keep people out of the polls and then claimed that we were the only Western democracy that does that, when, in fact, we are one of the only Western democracies that does not require photo ID when you go vote," he said.

Listen to the WND/Radio America interview with Hans von Spakovsky:

Von Spakovsky said no one knows how much voter fraud occurs, but he said the system is ripe for exploitation for several reasons. Some of the biggest vulnerabilities lie in outdated voter rolls.

"There's almost three million people who are registered in more than one state," he said. "How many of those are actually voting in more than one state at the same time, which is, of course, illegal? We don't know because nobody's actually checked that out to look at it."

Also on the rolls are many people who couldn't possibly show up to vote.

"There are almost two million people that are dead who are still on voter rolls across the country," von Spokovsky said. "How many of those are just an error, and how many are actually still voting because someone's using their name? Again, we don't know because there's never been any systematic check of that."

He said there is concrete evidence of dead people voting in some locales.

"Right before the election, a CBS TV station in Los Angeles actually started checking that. They found several hundred people just in Los Angeles who had been dead for years but had continued to vote in multiple elections," he said.

The problem, says von Spakovsky, is that proving voter fraud in past elections is very difficult.

"It's very difficult to investigate voter fraud cases. It's like the cases I just mentioned in California, several hundred people casting ballots after they died. Obviously somebody forged their signature, somebody forged their ballot," he said. "Trying to find out who that was is going to be pretty difficult."

So what can be done to strengthen election integrity in the future? Von Spakovsky said the first step is to get the most accurate voter rolls possible.

"The Justice Department has the ability to file suit because there is a federal law that requires state and local election officials to maintain the accuracy of their voter rolls, to clean them up, to take off people who have died and moved away," he said. "Many folks haven't been complying with that law, and the Obama administration knowingly and intentionally refused to enforce that provision."

The next step, he said, is to confirm who is actually eligible to vote.

"The Department of Homeland Security needs to start sharing its database on non-citizens in the country with election officials all over the country, so they can check it and find people who shouldn't be on the rolls because they're not U.S. citizens," von Spakovsky said.

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He said rooting out ineligible voters should also take place at the time they register.

"The other step that has to be taken, because of the fact that illegal aliens are being given driver's licenses, is that states have to put in requirements that you provide proof of citizenship when you register to vote," von Spakovsky said.

And he has one more idea.

"Juries are drawn from voter registration lists," he explained. "One thing that is not done consistently around the country is, when people are excused from jury duty because they're not a U.S. citizen, that information needs to be given by the local courts to local election officials so they can take those people off the rolls. That's not being done in many, many states."

Von Spakovsky would like to see all states adopt provisions requiring voters to present a photo ID at the polls, and he would extend that requirement to absentee voters as well, something he said most states with voter ID laws have not done.

And von Spakovsky said Trump could get the ball rolling on almost all of this without running it by Congress.

"A lot of it can be done administratively through the executive branch, which the Trump administration now controls, particularly the Department of Justice and the Department of Homeland Security," he said.

In addition to contending there isn't much of a voter fraud problem in the U.S., Democrats also assert that voter ID and other provisions could disenfranchise the most vulnerable citizens, namely minorities and the poor. Von Spakovsky said it's exactly the opposite.

"The victims (who have their votes stolen) in these cases often are the poor and minorities. An individual who was convicted of voter fraud up in Try, New York, just a couple of years ago was asked specifically why they were targeting poor minority neighborhoods. He said, 'They're the people least likely to notice or complain that their vote's been stolen,'" von Spakovsky said.

He added, "This effort will actually help the poor. It will help racial minorities and ensure their vote doesn't get stolen."