The Coalition has slipped further behind Labor, Bill Shorten's personal ratings have improved and Malcolm Turnbull has increased his lead over Tony Abbott as preferred Liberal leader, according to a new poll taken at the end of one the government's toughest weeks.

The latest Fairfax-Ipsos poll shows the government trailing Labor by 54 per cent to 46 per cent on a two-party preferred basis, a result, which if replicated on election day, would cost the Coalition up to 36 seats.