Last month's Ipsos-Mori poll saw a 7% jump in the Conservative rating and a 6% drop for the Lib Dems after their September poll showed a 13% Tory lead over the Lib Dems.
And this month's poll - to be published in tomorrow's Observer - sees more dramatic changes. The numbers are:
UK Polling Report's Swing Calculator computes these figures into a Hung Parliament where the Conservatives would be 38 seats short of an overall majority.
Jonathan Isaby