Montana Gov. Steve Bullock says he uses private email to communicate with staff only about political or campaign-related issues, but acknowledges the line between politics and state business sometimes gets blurry.

Those blurred lines came to light when Lt. Gov. Angela McLean wrote to Bullock using their private email accounts to express her frustrations about her position. McLean is resigning to take a job with the Office of the Commissioner of Higher Education next month.

Public officials from Sarah Palin to Hillary Clinton have faced accusations of circumventing open-records laws by using private emails to discuss official business.

Bullock said Friday that his administration doesn't have a policy on the use of private email, but he and his staff have never used private messages to conceal discussions of official state business.