Chicago, Illinois - Oprah Winfrey took a swipe at Republican vice presidential candidate JD Vance during her speech at the Democratic Party Convention in Chicago on Wednesday.

Vance had previously made offensive comments about childless women, referring to them as "childless cat ladies."

Oprah used the remark to point out that Americans are more united than some people might think.

"When a house is on fire, we don't ask about the homeowner's race or religion. We don't wonder who their partner is or how they voted," she said.

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"No, we just try to do the best we can to save them. And if the place happens to belong to a childless cat lady, well, we try to get that cat out, too."

Although she didn't mention Vance or Republican presidential candidate Donald Trump by name, the star emphasized the need to defend against bullies to protect freedom and democracy.

In her surprise appearance, Oprah focused the importance of decency and respect in the upcoming presidential election and urged independent and undecided voters to consider this when making their choice.

She also encouraged choosing "optimism over cynicism" and "common sense over nonsense," adding that Kamala Harris, the Democratic nominee, represents all of this.