J.J. Abrams has added his name to the more than 750 showrunners and screenwriters backing the Writers Guild’s battle against talent agencies taking packaging fees and owning production companies.

Abrams sent a message out Wednesday afternoon, four days after the letter of support was issued. The 15,000 members of the WGA will begin five days of online voting on Wednesday night on a “code of conduct,” which would require members to fire their agents if the agents have not signed on to the code by April 7.

“Last week I missed my opportunity to sign the Showrunners and Screenwriters Statement of Support,” Abrams said. “But I’m not going to miss my chance to vote. Please do the same. Please vote.”

“And if you agree with me that it’s finally time to end agencies’ conflicted practices, I urge you to join me and VOTE YES. Approve the Code of Conduct. Let’s give our Guild the power to make a difference for writers at every level and for generations to come,” he added.

The WGA is demanding the elimination of agencies receiving packaging fees and having ownership interest in affiliate production companies — demands that the agencies have insisted are not feasible. The WGA and Association of Talent Agents have held seven unproductive negotiating sessions since Feb. 5. After Tuesday’s session, both sides issued rancorous statements and blamed each other for the lack of progress. No new sessions have been scheduled.

The signers include most of the prominent showrunners and film scribes in the industry, including Shonda Rhimes, Greg Berlanti, Seth MacFarlane, Jenji Kohan, Eric Roth, Barry Jenkins, and David Koepp. Notable showrunners whose signatures were not on the letter include Ryan Murphy, Chuck Lorre, and Steve Levitan.

The ATA made counter-proposals at a March 21 session that contain provisions for more accountability and transparency by agencies for clients including giving writers consent over whether a television show is packaged. The negotiations are the first effort to revamp the 43-year-old franchise agreement.

Most scripted television is packaged by agencies, which forgo commissioning the client and receives a fee from the television studio. It’s become a particularly emotional issue over the past year with the WGA alleging that agents are disincentivized to get the best deals for writers when they are collecting packaging fees from studios.

Agencies have defended packaging as a means of creating employment. The ATA released a report last week which calculated that writers would have lost at least $49 million annually had they had to pay commissions on packaged shows.

Abrams is a formidable presence in Hollywood with directing credits on “Star Wars: The Force Awakens” and the upcoming “Star Wars: Episode IX.” He created or co-created ” Felicity,” “Alias,” “Lost,” and is an executive producer on “Westworld” and “Castle Rock.”