His organization does pick up a percentage of house - churches, which is an area that most researchers omit, due to the sheer difficulty in obtaining any information. (redeeminggod.com)
In addition to all the OTHER answers, another reason is the sheer difficulty. (politics.stackexchange.com)
There is a chance he could be put in a decisive position — a chance which, given the sheer difficulty both the Tories and Labour face in winning an overall majority, is far from insubstantial. (politics.co.uk)