What to Do?

I have been at this job for about a month and already my presence seems to have rubbed someone the wrong way. Not anyone in the office per se but a vendor we have a contract with. Apparently the vendor was hoping all the public relations/communicaitons work would be left to him and his company. But they decided to go ahead and hire someone. Then there was an issue about hiring lobbists. The vendor had people in mind, but then the president decide to go with a bigger, more established firm. This didn't sit well. Now the vendor seems to have a thing against me and has been trying to do anything to make me look bad. Luckily, I've been on my toes from the beginning. And I've been doing my job as best as I can to make sure that there are no complaints. I've been in situations like this before and I've been getting better at the game. I just hate the fact that there are those who prefer to play games rather than spend their energy actually doing their jobs well.