yeah, but, i want to do a good job. I'm under a ton of pressure right now and if i ever want to move up I gotta impress.
That makes sense, but unfortunately, if your input really is limited to a rating, then you don't really have an opportunity to do a good job either. If you say no there will never be any input on your choice. If you give a positive rating then they might compare their eventual rating to yours, but from your description I'm guessing they hardly look at it. The only possible bad outcome is that you rate somebody high enough for a second interview and they determine they're incredibly terrible.
So all you really have to do is filter out incredibly terrible people. This is easily done by asking yourself if you would actually want this person as a coworker at all.
You will do fine.
If you are really that concerned, the safest thing to do is just to say no hire, since it is almost impossible for that to come back on you in any way. But that would be immoral and I do not recommend it.