Hi Sara -
How quickly I forget! While reading your post I was flooded of memories of our daughter doing the SAME thing! It was really rough for quite some time for both mom and dad (our daughter did this pretty much her entire 2nd year)! My husband is a sweet, sensitive man so this was really heartbreaking for him. I hated to see him so hurt and at the same time was exhausted from being 'wanted' all the time by our daughter! I had heard it was a phase and it was - it passed and now there are some days that go by when she could care a less what I'm doing and ALL about Daddy. Luckily now she goes back and forth and we both get our fill of love and attention!
In the meantime, I would just talk up dad as another poster recommended (this didn't really work for my daughter but we still did it) and try to stay positive. My husband and I noticed the more he pulled away from her(when his feelings were hurt from her yelling "no!" to anything he offered to do) the more she'd pull away from him. It was really tough in the midst of it all for him to stay positive but continuing to act friendly and wanting her attention did seem to help at times. Also, there were times when I had to do things and she wanted nothing to do with daddy so she would have to sit and cry while I did them or was able to help her with whatever. I thought it was important to show her that we couldn't always be at her beck and call (especially whoever it was she preferred at the time) and I DID have to shower, use the bathroom, etc!!! I took that time to show her that mommy and daddy have needs too (bathing, bathroom, whatever) and that she had a choice btw us and she chose to cry/throw a fit instead of letting daddy help her.
Good luck - this too shall pass! :) :) :)