Obama Rebukes Trump for 'Rigged' Election ClaimsU.S. President Barack Obama rebuked Donald Trump Tuesday for claiming that the November presidential election is rigged against him, saying the Republican contender ought to "stop whining" and make his case to voters that he should win. "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," Obama said at a White House news conference. "It’s unprecedented. It happens to be based on no facts." WATCH: President Obama on Trump's claim No media source currently available As he has fallen behind in national polls against Democratic rival Hillary Clinton, Trump has recently questioned the legitimacy of the election. The brash real estate tycoon making his first run for elected office has contended, without presenting any evidence, that vote fraud is occurring as some states conduct early voting and that more would happen on Election Day, November 8. He says the election is rigged, with the national news media conspiring with Clinton, a former U.S. secretary of state, to make her the country's first female president. “I’d advise Mr. Trump to stop whining and go try to make his case to get votes," Obama said. "And if he got the most votes, it would be my expectation of Hillary Clinton to offer a gracious concession speech and pledge to work with him in order to make sure that the American people benefit from an effective government. And it would be my job to welcome Mr. Trump, regardless of what he’s said about me, or my differences with him or my opinions and escort him over to the Capitol in which there would be a peaceful transfer of power. That’s what Americans do.”\n\nObama, who leaves office in January after two terms in office, said, “There is no serious person out there who would suggest somehow that you could even rig America’s elections, in part because they’re so decentralized and the numbers of votes involved. There’s no evidence that that has happened in the past or that there are instances in which that will happen this time.” He told Trump, "You start whining before the game's even over. If whenever things are going badly for you and you lose, you start to blaming somebody else, then you don’t have what it takes to be in this job."\n\nThere is scant evidence of vote fraud in United States elections, with one study saying there were only 31 instances of voter impersonation from 2000 to 2014, a period in which one billion votes were cast in a long list of elections.\n\nObama, a staunch Clinton supporter, also criticized Trump's praise for Russian President Vladimir Putin. Obama said Trump's "flattery" of the Russian leader is "unprecedented in American politics."