Vice President Mike Pence will lead a commission to investigate voter registration issues, President Trump said Sunday.

In an interview with Fox News' Bill O'Reilly before Super Bowl LI, Trump - who shortly after taking office told congressional lawmakers that 3 to 5 million illegal votes had cost him the popular vote against Hillary Clinton - reiterated his concerns about voter irregularities, saying he planned to task his vice president with looking into concerns over voter registration.

"I'm going to set up a commission ... headed by Vice President Mike Pence, and we're going to look at it very, very carefully," Trump said.

Despite no credible evidence that any massive voter fraud occurred, especially on the scale Trump suggested, during the 2016 presidential race, the president has continued to push the theory, much to the chagrin of some of his aides and many congressional leaders.

His press secretary promised an investigation into the issue, although a rumored executive order to launch an inquiry has so far been postponed.

On Sunday, O'Reilly pressed Trump on his penchant for making dubious claims without having "the data to back it up," and the president seemed to narrow his focus from large-scale voter fraud to irregularities with voter registration.

"It has to do with the registration, and when you look at the registration and you see dead people that have voted," Trump said. "When you see people that are registered in two states, that have voted in two states, when you see other things, when you see illegals, people that are not citizens, and they are on the registration roles."

Indeed, it can be common for voters to be on the rolls in multiple states, something Trump has cited as evidence of intentional voter fraud. The Washington Post has found at least five Trump family members or top administration appointees who were registered in two states during the 2016 election, including Jared Kushner, Trump's son-in-law, and Stephen Bannon, his chief strategist.

"Look, Bill, we can be babies, but you take a look at the registration, you have illegals, you have dead people you have this, it's really a bad situation, it's really bad," Trump concluded.

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