I don't think you can keep you employer out of it? (from my days as middle management)
I think you have to go through your manager / HR first to resolve the issue before you can go further, as the employer has to have a chance to resolve it under workplace grievances. Under the law your employer is legally responsible to provide you a safe and bully free work environment.
I would keep records about encounters / incidents, report them you manager or HR, don't just report it, TELL manager / HR what outcome you are trying to achieve, and if this can't be resolved in-house, then you'll be forced to take the matter further... by reporting it (which ever gov dept that handles work related disputes in your state).
Where every possible keep a paper trail, diary entries of bullying, whom it's been reported to, outcome, meetings etc... keep good records, if it is taken to a tribunal then you'll be in the best position for a favorable outcome..
If all else fails maybe follow dazza 38 advice....
Good luck..
Regards Keith