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.

In September 2015, an officer who oversaw a preliminary hearing recommended that the case be heard by a misdemeanor-level tribunal and said imprisonment wasn’t warranted. But the next month, McCain, chairman of the Senate Armed Services Committee, told a reporter that the panel would hold a hearing if Bergdahl was not punished. In December, Gen. Robert B. Abrams sent Bergdahl’s case to a general court-martial, rejecting the hearing officer’s recommendation.

Legal experts have said that it will be hard to convince a judge to throw the charges out but that Army officers may have understood McCain’s comments as a tacit threat to their careers. A spokesman for McCain didn’t immediately respond to a message seeking comment early Tuesday morning.

The judge overseeing Bergdahl’s case decided Monday that Abrams must testify this week after hearing arguments on a separate motion.

The judge, Army Col. Jeffery Nance, said he wants to question Abrams about approximately 100 letters Abrams put in a “burn bag” to be incinerated. Abrams has the option to testify in person or by phone.

“There are some questions I have to ask about the 100 or so letters,” Nance told the lawyers, though he said he was skeptical about the letters’ relevance.

The destruction of the letters is one of several reasons the defense says Abrams should be disqualified from the case. They also cite his prior role advising former U.S. Defense Secretary Chuck Hagel during efforts to return Bergdahl from captivity and questions about whether Abrams considered defense objections to the findings of a preliminary hearing.

The defense is seeking a reset in the case that would allow another commander to decide whether it warrants a general court-martial.

Prosecutors say the letters, sent largely by members of the public, didn’t constitute evidence and that Abrams shouldn’t be required to testify, nor should he be disqualified.

Defense attorney Eugene Fidell argued that the letters were valuable for reasons including that they may have contained leads that Bergdahl’s lawyers could have pursued.

The judge also said Monday that defense attorneys can propose a significant revamping of pretrial deadlines and he may consider changing the February 2017 trial date in the future.

The defense has argued that trial deadlines have been jeopardized by the pace at which prosecutors are handing over classified information. Prosecutors acknowledged Monday that they were likely to miss an upcoming deadline on the documents, saying it’s taking time to get military and intelligence agencies to review them.

Bergdahl, who is from Hailey, Idaho, walked off his post in Afghanistan in 2009 and wound up as a captive of the Taliban and its allies until 2014. The Obama administration won his release by swapping him for Guantanamo Bay detainees. Bergdahl faces a court-martial on charges of desertion and misbehavior before the enemy, the latter of which carries up to a life sentence.

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