The problem with being at war and abysmal (what 90% of the cases are), ist that you canno get a higher standing with them unless you gift them regions, and even then it won't improve too greatly:
I gave them a region (Helsinki) for fun. Relations went from abysmal to amiable but I couldn't get any more negotiations through after: The AI was "annoyed" for some reason that they accepted my region gift ?

Next turn I try to offer a ceasefire, for huge costs (regions) which of course is not something i really needed as I might as well squash them. So I just loaded my old game and finished them off.