Obama on Trump's election rigging claims: 'Stop whining'

President Obama criticized Donald Trump for suggesting the presidential election is rigged.

"I have never seen in my lifetime or in modern political history any presidential candidate trying to discredit the elections and the election process before votes have even taken place. It's unprecedented. It happens to be based on no facts," the president said during a news conference at the White House, according to ABC News.

As early voters head to the polls, Trump's rigged election rhetoric continues on the campaign trail.

"They even want to rig the election at the polling booths where so many cities are corrupt to the cities voter fraud is all too common," Trump said.

Trump claims the election is rigged to help his opponent Hillary Clinton. He pointed to big cities such as Philadelphia, Chicago and St. Louis as examples of voter fraud.

But it's Indiana, home of Trump's running mate, Governor Mike Pence that is in the process of investigating voter fraud. After checking with the government website, indianovoters.com, some voters believed they weren't registered to vote because their names or date of birth were changed. Indiana officials said it may have been legitimate mistakes.

"We are confident the system has not been hacked," Connie Lawson, Indiana Secretary of State, said.

Meantime, while Chicago has had a history of voter fraud, in recent years, the Board of Elections said technology has helped the system become and remain very secure.

"In the past 10 years, we've had nine million ballots cast out of those we've only had to refer 10 matters to the Cook County States Attorney's Office," Marisel Hernandez, Chicago Board of Elections chairwoman, said.

While many election officials nationwide are defending their voting systems, President Obama weighed in on Trump's latest claims.

"I'd advise Mr. Trump to stop whining and go try to make his case to get votes," he said.

Many Republicans have disputed Trump's claims that the election is rigged.

ABC News contributed to this report.