P.C.
I went through this with my daughter, around the same age. I, too, believe it is a phase that will be outgrown... However, it may also be a control issue (it was with my daughter). She was controlling the situation by dictating who would do what for her in the household. What helped with us was my absense. I would simply leave, so I was not available to do certain things (i.e., brush teeth or put her to bed). When my husband was the only one there to do it, she would be more readily compliant and then grew accustomed to someone other than Mommy doing it for her.
I hope this is helpful. I truly understand what you're going through!