An 'October surprise' could still spell trouble for Kamala Harris, Hillary।

Kamala Harris and Donald Trump’s campaigns can’t get too comfortable in the final weeks leading up to the presidential election. An “October surprise” might be around the corner.

Trump’s 2016 opponent, Hillary Clinton, is all too familiar with how an October surprise – a major, unexpected news story about a candidate – can derail a campaign during its final stretch and ultimately influence the outcome of an election. Hers came less than a month before Election Day, when Wikileaks began releasing her emails.

She’s now warning Harris to expect an October surprise of her own.

“I anticipate something will happen in October, as it always does,” Clinton said in a recent interview with PBS. “…There will be concerted efforts to distort and pervert Kamala Harris, who she is, what she stands for, what's she's done

Clinton said she was especially concerned about social media disinformation circulated by Russia, Iran, and China, as well as the pro-Trump media organizations that may pick up any fabricated stories.

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"I anticipate there will be a full-court press in October. The digital airwaves will be filled.”

In the age of the 24/7 news cycle, stories affecting the presidential candidates can break at any moment. But October surprises are not a modern phenomenon. Here’s how they’ve influenced elections in the past.

Though the term was not coined until 1980, the original October surprise came during the 1840 U.S. presidential election, according to POLITICO.

President Martin Van Buren attempted to deploy an October surprise against the Whig Party when he accused top party officials of a “most stupendous and atrocious fraud” in which they paid Pennsylvania voters to travel to New York and cast fraudulent ballots in the state’s 1838 election.