MISSOULA, Montana (Reuters) - A Montana bride who was accused of pushing her new husband to his death from a cliff in Glacier National Park pleaded guilty to second-degree murder on Thursday in an 11th-hour deal with prosecutors that will spare her from a mandatory sentence of life in prison. In exchange for the guilty plea, prosecutors agreed to drop first-degree murder charges that could have carried a mandatory life sentence, should she have been convicted, as well as charges of lying to law enforcement. Graham is scheduled to be sentenced on March 27. Graham, in admitting her guilt, told the judge that on the day her husband died, the couple had driven to the park and walked down to an embankment on the cliff face, where she told Johnson she wasn't happy and "wasn't sure we should be married." He responded by grabbing her hand, she said. "I told him to let go and I pushed his hand off," Graham said. I just pushed his hand off and just pushed away. U.S. District Judge Donald Molloy asked her if, after that, she knew Johnson had fallen over the cliff, and Graham responded that she did. Before accepting the plea, the judge warned Graham that by pleading guilty she was "possibly looking at spending the balance" of her life in prison. She responded that she understood the consequences. While a second-degree murder conviction may be punishable by life in prison, it can also result in a lesser sentence of about 20 years behind bars, with possible adjustments for accepting responsibility and other factors. U.S. Marshals led Graham away in handcuffs after the hearing, during which her mother cried in court. Graham had been in her parents' custody and under electronic monitoring pending trial. Federal prosecutors contended that Graham deliberately shoved her husband off a rock ledge while the couple was hiking a steep trail at Glacier and then lied to investigators and tried to cover up the crime. Graham's public defender, Andy Nelson, told reporters his team was "drained" and that the case had been "a long, emotional process." Jury selection in the case began on Monday, and on Thursday morning defense attorneys mounted their side of the case by, among other things, showing a video of Graham and Johnson dancing closely at their wedding and presenting evidence she had paid an artist to write a customized song for the couple. Additional reporting by Alex Dobuzinskis and Dan Whitcomb in Los Angeles; Writing by Dan Whitcomb; Editing by Cynthia Johnston, Leslie Adler, Kenneth Barry and Lisa Shumaker