The future of Showtime’s long-running series “Shameless” is being held up, due to ongoing negotiations with star Emmy Rossum.

Rossum, who’s been a lead on “Shameless” since it debuted in 2011, is in the midst of re-negotiating her contract for a potential eighth season. Sources close to the show tell Variety that months ago, the actress was offered pay parity with her co-star William H. Macy — but she is asking to be paid more.

An insider says Showtime wants to renew the show for Season 8, but won’t proceed until resolving Rossum’s salary. The creative forces behind the dramedy have not even considered a plan for the show to continue without her, our source explains, as all parties involved are hopeful to close negotiations with the actress.

Rossum is demanding equal pay with Macy, after seven seasons of being paid less than him, according to a report published earlier today by the Hollywood Reporter. A source tells Variety she has in fact been offered equal pay. But she is holding out for a bigger salary than Macy to make up for the previous seasons where she was making significantly less than him.

Both Showtime and Warner Bros. TV, the studio behind “Shameless,” declined to comment. Reps for Rossum didn’t immediately respond to Variety‘s calls.

A source close to “Shameless” tells Variety that the network and studio take the income disparity very seriously, but insist that the offer for parity has been on the table for a while and is not being accepted by Rossum’s team. By offering her the same salary as Macy, this person says the network and studio are “clearly acknowledging her importance to the show” and how her role has evolved into a crucial part over the years. “It hasn’t even been contemplated doing the show without her,” adds the source.

Rossum’s salary dispute comes at a time when equal pay has become a prominent conversation in the industry, led by actresses like Patricia Arquette and Jennifer Lawrence.

At the time “Shameless” premiered, Macy, 66, was arguably more well-known than Rossum, 30. Though the actress was coming off of films like “The Day After Tomorrow” and “Phantom of the Opera” for which she was nominated for a Golden Globe, Macy had already won multiple Emmys, plus had an Oscar nomination, Golden Globe and SAG nominations.

For his work on “Shameless,” Macy has been nominated for three Emmys, a Golden Globe, and won a SAG Award. Rossum has been nominated for two Critics Choice Awards, but never an Emmy, SAG Award or Golden Globe. Awards recognition typically helps actors to negotiate a pay raise.

Rossum has renegotiated her salary since “Shameless” debuted. An insider says she got a significant increase from her original deal several seasons ago, as did Macy. Macy recently closed a new deal for the potential eighth season — the same deal that is now being offered to Rossum.