WASHINGTON -- An Army major general has denied Chelsea Manning's request for clemency and upheld her 35-year sentence for leaking sensitive government documents to WikiLeaks, in a move that will kick off the appeals process in the high-profile case.

Maj. Gen. Jeffrey S. Buchanan's decision was announced in a Monday press release from the U.S. Army Military District of Washington. As the commanding authority for Manning's court martial, Buchanan had under military law the power to approve or reject the results of the trial judge, Col. Denise Lind.

Manning's supporters had flooded Buchanan with over 3,000 letters of support, but his move was nonetheless widely expected.

"It's no surprise that the convening authority denied this request. We anticipated it, and we're prepared to go forward with the appeal," said Nancy Hollander, Manning's recently selected appeals lawyer. "We did not expect any relief from the general. But we do believe that we will go forward with the appeal, and that was always what we intended to do."

Manning has been held in military prison at Fort Leavenworth in Kansas since shortly after she was sentenced in August 2013 for leaking the military reports and other documents. Formerly known as Bradley, she began legal proceedings last month to formally change her first name to Chelsea. She is seeking treatment for gender dysphoria from the Army, which currently bans service by transgender persons.