EXCLUSIVE: Criminal Minds veterans Joe Mantegna and Matthew Gray Gubler have closed new deals to continue on the long-running CBS drama series, recently renewed for a 13th season. However, I hear Kirsten Vangsness and A.J. Cook are currently at an impasse in their negotiations as the actresses are seeking parity with their male co-stars.

The duo, who are negotiating together, took a similar stand during the 2013 negotiations as the two at the time consistently had been paid less than half of what their male counterparts including Gubler and Shemar Moore were making. Back then, Vangsness and Cook eventually reached new agreements with ABC Studios, CBS TV Studios and CBS, though I hear they are willing to walk this time if they don’t get some parity with their veteran co-stars, putting the return of their respective fan-favorite characters Penelope and J.J. in limbo. I hear the studios behind the series did not begin talks with Vangsness and Cook until after completing deals with Mantegna and Gubler.

In addition to Mantegna and Gubler, set to return next season are recent Criminal Minds cast additions Adam Rodriguez, Damon Gupton and Aisha Tyler along with Paget Brewster, who rejoined the crime drama this season after a four-year break.

ABC Studios and CBS were taken to task on the treatment of Criminal Minds female cast members in 2010 when they opted not to bring back Cook for Season 6 and to reduce the episodes of Brewster, leaving Vangsness as the only remaining full-time female cast member. The move led to an outcry from fans. Cook and Brewster subsequently were reinstated.

Both Vangsness and Cook have been on Criminal Minds since the beginning. Vangsness started as a recurring in Season 1, quickly getting promoted to a regular. She also co-starred on the 2011 spinoff Criminal Minds: Suspect Behavior. Cook has been a series regular for the entire run except for Season 6, when she guest starred.

CBS sibling Showtime and Warner Bros. TV recently went through a similar push for parity on Shameless for stars Emmy Rossum and William H. Macy, as did CBS and WBTV on The Big Bang Theory, with co-stars Mayim Bialik and Melissa Rauch seeking pay on par with their co-stars’. Both lengthy negotiations reached successful conclusions, which observers are also hoping for on Criminal Minds.