The seat is the Tories' number 75 target with a projected Labour majority of 3,021.
Ms Cash resigned at a special meeting of the Association tonight - also attended by Eric Pickles and Lord Strathclyde - following internal tensions in the local party.
9.45pm: CCHQ mounting effort to reverse decision.
Tuesday morning: More at The Daily Mail.
Tuesday 8pm update: CCHQ are informing the press that "Joanne Cash remains the Conservative candidate for Westminster North"
