US President Barack Obama on Tuesday sharply chided the Republican presidential candidate Donald Trump for his unsupported claims that the presidential election is rigged against him.

Obama urged Trump to "stop whining" and instead go and make his case to voters.

The President made the comments during a non-campaign event alongside Italian Prime Minister Matteo Renzi at the White House.

"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 "It's unprecedented."

Obama emphasized that there is simply no evidence of electoral fraud, stressing that elections are run by state and local officials from both major US parties. Obama said that if a candidate starts whining before the game is even over, "then you don't have what it takes to be in this job."

Trump has long held that the electoral process is rigged. On Monday he tweeted: "Of course there is large scale voter fraud happening on and before Election Day."

That same day, the real estate mogul also told a rally in Green Bay, Wisconsin the same thing.

Trump's flattery of Putin 'unprecedented'

Obama also blasted Trump's apparent flattery of Russian leader Vladimir Putin, something he also described as "unprecedented" and "out of step" with the rest of the US political establishment.

However, although he claimed he was no longer surprised by Trump's comments, Obama expressed dismay that a number of Republican lawmakers were falling in line with their nominee's controversial stances. "I'm much more surprised by Republican officials now supporting and in some cases echoing” Putin's policy approaches, Obama said.

"It's quite a reversal," he added. "You'll have to ask them to explain it."

Obama plays down Clinton emails

Notes recently released by the FBI show discussions between the agency and state department officials as to the classification of an email from Democratic presidental candidate Hillary Clinton's private server.

Trump had come out saying that the FBI records showed a "criminal act." Critics say the email showed that the FBI expected favors in exchange for reducing the classification status of Clinton's emails.

Obama disputed this as "just not true," saying that such interactions between the FBI and State Department happened frequently.

dm/se (AP, Reuters)