Julianna Margulies is to executive produce Sister Senators.

The ER star, 60, is to team up with Emily Harrold, who will direct the documentary feature film, according to Deadline.

Sister Senators will tell the story of the alliance between South Carolina State Senate's Republican senators Katrina Shealy, Sandy Senn, Penry Gustafson, Democrat Margie Bright Matthews, and Independent Mia McLeod, after they joined forces to form a fierce pro-choice coalition, successfully blocking a near-total abortion ban.

Margulies did "anything" she could to be part of the project.

She said: "After seeing just a few minutes of footage from this project, I knew I had to do anything I could to be involved.

"At a moment when women's rights are being trampled upon, we need examples of powerful women who are willing to put people before partisan politics.

"How can 41 men decide what a woman can and cannot do with their own body?

"Without women in legislative bodies how can we protect ourselves? We must have female voices defending our rights."

Filmmaker Harrold is delighted to have Margulies on board.

She said: "Having Julianna join this project means the world to us.

"She brings a passion for telling complex nuanced stories of women fighting against immeasurable odds.

"We're so excited to be working with her to bring this project into the world."

According to Deadline, Sister Senators is in early post-production.

Margulies previously portrayed Laura, a gay reporter, in the hit TV series The Morning Show.

But Margulies, who is not homosexual, came under fire from some for playing the character.

Speaking on CBS Mornings, she previously said: "I understand 100 percent that I can't play a different race, but I am an actress and I am supposed to embody another character.

"Whatever their sexuality is doesn't matter to me, the same way watching a gay person play a straight person [wouldn't].

"Are you telling me that because I'm a mother, I can never play a woman who has never had a child? Or if you've never been married that you can never play a married woman?"