The British parliament defeated Prime Minister Boris Johnson's timetable to rush the deal's legislation through the House of Commons in just three days, making ratification of his deal by the Oct. 31 deadline almost impossible.
The local share price index futures fell 2 points, a 0.4pc discount to the underlying S&P/ASX 200 index close. The benchmark rose 0.3pc on Tuesday.
Across the Tasman sea, New Zealand's benchmark S&P/NZX 50 index fell 0.9pc or 104.8 points to 10,985.58 in early trade.