Complex sentence: Attempts have been made within the Bristol region to call for the establishment of an ITA, but so far these have been rejected by the three other unitary authorities of North Somerset, Bath and North East Somerset and South Gloucestershire.
Split into simpler sentences: Attempts have been made within the Bristol region to call for the establishment of an ITA. So far, these have all been rejected by the three other unitary authorities of North Somerset, Bath and North East Somerset and South Gloucestershire.