It is definitely a power struggle. Think like a kid for a minute: Is it fun to go potty? More fun than watching a movie or playing with your toys? What's fun about it? NOTHING. It's just something you have to do that nobody ever really "wants" to do - a "necessary evil" if you will.
We had to instill the "potty first" rule. About every 20 minutes or whenever our oldest wanted to change activities, "potty first". You can have a glass of juice, but "potty first". You can watch a movie instead of coloring, but "potty first". If it's been about 20 minutes, and she hasn't gone, "You can play with your toys, but potty first".
When she complains, remind her that if she were going potty "like she knows how to" then you wouldn't be doing this.
That's how we resolved our pottying issues.
For what it's worth, and good luck!