Barack Obama has warned of the fragility of American democracy, making reference to the rise of Nazi Germany in the 1930s.
Speaking during a question and answer session at the Economic Club of Chicago on Tuesday, the former US president warned against growing nativism in America.
“We have to tend to this garden of democracy or else things could fall apart quickly,” Mr Obama said.
“That's what happened in Germany in the 1930s which, despite the democracy of the Weimar Republic and centuries of high-level cultural and scientific achievements, Adolph Hitler rose to dominate,” he said, according to newspaper Crain’s Chicago Business.
“Sixty million people died,” he added. “So, you've got to pay attention. And vote.”
Although Mr Obama did not mention Donald Trump by name, some believed his comments were aimed at the current US president and his “Make America Great Again” rhetoric - which critics argue has fuelled nationalism.
Mr Trump has been accused of fuelling anti-Muslim sentiment across the US.
In November, the President came under fire for retweeting inflammatory videos from the Twitter account of a British far-right, ultra-nationalist figure, which contained anti-Muslim content.
His actions were publicly rebuked by prime minister Theresa May, whose official spokesperson condemned the president's actions as "wrong".