Former President Barack Obama warned a Chicago audience earlier this week that a “Hitler” could rise in America unless people “pay attention.”

“We have to tend to this garden of democracy or else things could fall apart quickly,” Obama said, according to Crain’s Chicago Business. “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.”

“Sixty million people died,” he continued. “So, you’ve got to pay attention. And vote.”

Obama made the remarks during a question-and-answer session at the Economic Club of Chicago, where he also warned against growing levels of nativism in America. Although he did not refer to any particular individual, his comments were interpreted by some as a rebuke to President Donald Trump.

Since leaving office in January, Obama has traveled around the world speaking at dozens of different events, often for incredibly high fees.

Although he generally refrains from criticizing the current administration directly, Obama has occasionally spoken out on issues he feels are most important.

In January, barely more than a week after Trump took office, Obama criticized the new administration’s executive order on immigration. A spokesman, Kevin Lewis, said: “the [former] President fundamentally disagrees with the notion of discriminating against individuals because of their faith or religion.”

In September, he attacked Trump’s plans to end the Deferred Action for Childhood Arrivals program, describing it as “cruel” and “wrong,” and last week lamented a “temporary absence of American leadership” on the issue of climate change.

Follow Ben Kew on Facebook, on Twitter at @ben_kew, or email him at bkew@breitbart.com.