A campaign protesting the planned HBO series “Confederate” flooded social media Sunday night, with viewers tweeting #NoConfederate in massive numbers during “Game of Thrones,” propelling the hashtag to Twitter’s No. 1 trending spot in the U.S. and No. 2 worldwide.

“We have great respect for the dialogue and concern being expressed around ‘Confederate,'” HBO responded in a statement. “We have faith that [writers] Nichelle, Dan, David and Malcolm will approach the subject with care and sensitivity. The project is currently in its infancy so we hope that people will reserve judgment until there is something to see.”

“Confederate” tells an alternate version of history in where the South has seceded from the Union… and slavery has remained legal and continued into the modern era.

Also Read:HBO President Addresses 'Confederate' Backlash: 'It's a Risk Worth Taking'

The story takes place during what’s called the Third American Civil War and follows a group of characters on both sides of the Mason-Dixon line, now a demilitarized zone. The characters include freedom fighters, slave hunters, politicians, abolitionists, journalists and the executives of a slave-holding conglomerate and the families they control.

Backlash began almost immediately after HBO’s announcement, with many saying white executive producers David Benioff and D.B. Weiss — showrunners of “Game of Thrones” — were wrong for the material. The show is also executive produced by African-American writers Nichelle Tramble Spellman and her husband, Malcolm Spellman.

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HBO has said that people should reserve judgement until the show’s premiere, which has not yet been scheduled.

“The bet for us is on our talent,” HBO President Casey Bloys said at Television Critics Association press tour on Wednesday. “We have a long history at HBO of betting on our talent, and we’re going to stand behind them … These four writers are at the top of their game. They could do anything they want. But this is what they feel passionately about, so I’m going to bet on that.”

Bloys added, “They feel — and I support them — it’s a risk worth taking.”

Malcolm Spellman told NPR last week that he and his wife feel marginalized by African-American critics who suggested they should not have signed on.

“Regardless of how awkwardly that press release was phrased, we are involved as peers, as full executive producers and as partners,” he said, referring to the initial announcement of the project. “If you render us a footnote, the assumption is that we’re just a prop or a shield…Our own people marginalized us like that.”

Also Read:'Confederate' Debate: Can 'Game of Thrones' Duo Handle Slavery Responsibly?

Related stories from TheWrap:

HBO President Addresses 'Confederate' Backlash: 'It's a Risk Worth Taking'

'Confederate' Producers on Backlash: We Know We're 'Dealing With Weapons-Grade Material'

'Confederate' Debate: Can 'Game of Thrones' Duo Handle Slavery Responsibly?

'Game of Thrones' Showrunners Reveal Next HBO Project: 'Confederate'