Margot Robbie at the London premiere of "Barbie" on July 12. (Maja Smiejkowska/Reuters)

(CNN) — Fran Drescher, president of the Screen Actors Guild-American Federation of Television and Radio Artists (SAG-AFTRA) announced during a press conference in Los Angeles on Thursday that the union representing Hollywood actors will go on strike.

“It’s official @sagaftra has voted to strike. We will be joining the @wgawest @wgaeast on the picket lines starting tomorrow,” Yvette Nicole Brown wrote in a post on her Instagram page on Thursday as news of the strike became official.

She added, “In preparation we all got together last week to create our signs. I was on sticks! When you’re out there without a splinter thanks to the perfectly placed duct tape, think of ya girl! #UnionStrong.”

The official strike declaration comes after SAG-AFTRA’s negotiating committee’s talks with major studios and streaming services about a new contract failed, even after the original deadline to make a deal was extended by weeks and a federal mediator got involved.

The strike is set to go into effect at midnight PT Thursday night, but many actors have spoken about the impact it will have before it officially commenced.

On the red carpet of the “Oppenheimer” premiere in London – moments before the cast walked out in solidarity of the strike – Matt Damon told Deadline that a strike will impact his new production company that he started with Ben Affleck.

“It’s going to be tough for the actors, for 160,000 actors. Nobody wants a work stoppage,” Damon added. “But if our leadership is saying that the deal isn’t fair then we’ve got to hold strong until we get a deal that’s fair for working actors.”

Margot Robbie, who stars in the upcoming “Barbie” movie, told Sky News during the movie’s London premiere Wednesday night that she’s “absolutely” in support of a SAG-AFTRA strike.

“I very much am in support of all the unions and I’m a part of SAG, so I would absolutely stand by them,” she said.

“Abbott Elementary” actor Sheryl Lee Ralph was nominated for an Emmy on Wednesday, but she told The Hollywood Reporter in an interview published shortly after her nod was announced that the news is bittersweet.

“We’re fighting for our art,” Ralph said, adding, “We’re fighting for what we love, and what we know people love. We’re not big million-dollar companies. No, we’re people, and we want to enjoy what we do, and we want to make a living at it. That’s what this is about.”

Throughout the day on Thursday, more actors took to their social media following news of the strike to express their support.

“And Just Like That” star Cynthia Nixon said in a statement posted to her Twitter page that she is “proud to be standing tall” with the WGA as a member of SAG “as actors and writers together demand a fair share of the record-breaking profits the studios have been reaping from our labor for far too long.”

“We will win this!” Nixon exclaimed.

Josh Gad, known for playing Olaf in Disney’s “Frozen” franchise, also tweeted how “proud and impressed” he was by Drescher and his union during Thursday’s press conference.

Bob Odenkirk, who was nominated on Wednesday for an Emmy for his performance in “Better Call Saul,” echoed Gad’s sentiment, writing on his Twitter page, “Holy Cow. Go Fran Go! This was a powerful statement. I stand with Fran and everyone in SAG and WGA in this extended moment…onwards.”

And Oscar-winner Jamie Lee Curtis showed her support by posting a photo on her Instagram page of theater masks with words saying, “It looks like it’s time to take down the masks and pick up the signs.”