Attorneys for Army Sgt. Bowe Bergdahl said Saturday they may seek a deposition from presidential contender Donald Trump or call him as a witness at a legal proceeding, saying they fear his comments could affect their client's right to a fair trial.

Bergdahl's attorney Army Lt. Col. Franklin Rosenblatt asked Trump in a letter dated Saturday for an interview to discuss the Republican's comments about Bergdahl, who faces military charges after walking off a post in Afghanistan in 2009. The letter sent to Trump's New York office by registered mail says the interview would determine whether they will seek to have him give a deposition or appear as a witness at a legal hearing.

"I request to interview you as soon as possible about your comments about Sergeant Bergdahl during frequent appearances in front of large audiences in advance of his court-martial," Rosenblatt wrote in the letter on U.S. Army letterhead.

Defense attorney Eugene Fidell said Trump's statements could affect Bergahl's right to a fair trial. He added in an email to The Associated Press that the statements "raise a serious question as to whether he has compromised Sgt. Bergdahl's right to a fair trial."

A spokeswoman for Trump's campaign didn't immediately respond to an email and a phone call seeking comment.

Fidell had previously asked publicly that Trump cease making comments about Bergdahl such as Trump's comment in October that the soldier was a "traitor, a no-good traitor, who should have been executed." Fidell has also said previously that Trump gave incorrect information about rescue efforts for Bergdahl during public speeches.

Bergdahl faces charges of desertion and misbehavior before the enemy, a relatively rare charge that carries a punishment of up to life in prison. His trial had been tentatively scheduled for the summer, but legal wrangling over access to classified documents has caused delays.

Bergdahl, of Hailey, Idaho, walked off his post in eastern Afghanistan on June 30, 2009, and was released in late May 2014 as part of a prisoner swap, in exchange for five detainees in Guantanamo Bay. The move prompted harsh criticism, with some in Congress accusing President Barack Obama of jeopardizing the safety of the country.

He was arraigned in December but has yet to enter a plea.