FORT BRAGG, N.C. (AP) — Attorneys for Army Sgt. Bowe Bergdahl are scheduled to argue Tuesday that decision-makers with power over the soldier’s prosecution were improperly swayed by negative comments from U.S. Sen. John McCain.

The defense argues that the chain of events surrounding Bergdahl’s prosecution shows “impermissible meddling” by McCain and says either the charges should be thrown out or Bergdahl should face no punishment if convicted. McCain, chairman of the Senate Armed Services Committee, has said the panel would hold a hearing if Bergdahl weren’t punished.

Legal experts say it’ll be hard to convince a judge to throw the charges out.

Bergdahl faces military charges after walking off his post in Afghanistan in 2009 and wound up as a captive of the Taliban and its allies until 2014.

Bergdahl is from Hailey, Idaho.