Have you ever worked with someone that seemed to suck the life out of the air as he walked by? Maybe you have worked with someone with an ego so large you marveled how she could get her head through a door. In the Laws of Project Management, you are doomed to be stuck with someone who is as smooth as sandpaper and as subtle as a Three Stooges marathon. So what do you do?
You do have options. Maybe you will decide to engage in an eternal struggle with this individual throughout the life of the project so you can achieve martyrdom and sainthood. If you choose this route, you are taking the path of being right. While on this course, you will be given many opportunities to see the glaring flaws of your nemesis. You may have many conflicts and battles which you may or may not overcome after much blood letting and justifying of position. The project may fail, but that's okay because you are right.
Another path you might choose is the road called Project Success. On this road, instead of reaffirming how difficult the other individual might be you take another stance. You determine how you can work with this individual so the project can be successful, even if that means you give up being right and making the other person wrong. Ask yourself, "why is it important that this person is involved with my project"? Value is often more than the work a person provides. It could include expertise, knowledge and even political support. If you can see the value this person could add, then as the project manager, you will want to ensure that value is provided for the success of the project.
Sometimes people are not deliberately being difficult or uncooperative, they just don't see the value of working with you on the project. Remember if the value they receive from a successful project is greater than the value of aggravating you, you might have a much smoother ride than you have been experiencing.
So the bottom line comes down to what you want as a project manager. Do you want to be right or do you want the project to succeed? It is not always possible to have both, but I have found success is more satisfying than "being right".