Mongolia has expressed limited sentiments towards joining TPP but they try to remain neutral between the various regional and global factions, and being a member of TPP could irritate their Russian and Chinese partners.
TTIP is similar, but you might as well just say TTIP if you mean TTIP and not TTP. Also, even if the UK is partner, Mongolia certainly can't be, at least to this particular partnership.
Mongolia has expressed limited sentiments towards joining TPP but they try to remain neutral between the various regional and global factions, and being a member of TPP could irritate their Russian and Chinese partners.