"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 joint news conference at the White House with Italian Prime Minister Matteo Renzi.
"If you start whining before the game's even over? If whenever things are going badly for you and you lose, you start blaming somebody else, then you don’t have what it takes to be in this job," Obama said, pointing to the Oval Office behind him. "I'd advise Mr. Trump to stop whining and go try to make his case to get votes."
Obama added that he would welcome Trump as the next president if he wins the election.
In recent days, the GOP nominee has ramped up his claims that the election will be rigged.