US TV host Oprah Winfrey has made a surprise, unannounced appearance at the Democratic National Convention in Chicago.

Oprah fired up the crowd in a speech on night three of the nomination convention for Kamala Harris and her running mate Tim Walz.

“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.

"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.”

The comment is a reference to Trump's running mate, JD Vance, who made a now-famous comment about childless women.

In 2021, Senator Vance said in an interview that the US was governed by “a bunch of childless cat ladies who are miserable at their own lives and the choices that they’ve made and so they want to make the rest of the country miserable, too.”

Oprah, whose production company is based in Chicago, does not have any children.

"Sweet promise of tomorrow, we're not going back," Oprah told delegates, leading to chants of "not going back".

Tracy Prince and Kathy Sykes jumped out of their seats when they saw Oprah, who was born in their home state of Mississippi, take to the stage.

“We love Oprah so much,” Mrs Sykes told BBC News. “Everyone in Mississippi is so proud that she claims us.”

She said Oprah’s speech was a “powerful message” to independent voters in particular to vote for Ms Harris.

“She gave very good reasons why - to choose common sense over nonsense,” Mrs Sykes said from the convention hall.

Wednesday night also included cameos from several entertainment celebrities including Stevie Wonder, Mindy Kaling and Kenan Thompson.

The Democratic Party is calling upon its famous members to help get eyes on this convention, hoping their presence will get voters to pay attention - and then maybe cast a vote for Kamala Harris in November.

It's a common tactic in US politics. The Republican National Convention last month featured appearances from rock musician Kid Rock and wrestler Hulk Hogan.