The Conservatives have a record 20-point lead over Labour, six points up on last month. Labour support has fallen two points to 25%, the lowest recorded in the ICM polls, which began in 1984.
Conservative support, at 45%, is at a 20-year high. That would give David Cameron a landslide victory as big as Labour's win in 1997, with some 400 seats. Labour might be reduced to well under 200 MPs, with many ministers losing their seats. The Tories would retain Crewe and Nantwich, won in a byelection last month, while Labour would lose previously safe seats such as Wakefield.
Conservative support has increased four points since last month's Guardian/ICM poll, and three points since another more recent ICM poll. Labour support has dropped two points since the last Guardian survey.
Liberal Democrat support, at 20%, is two points down but remains only five points behind Labour, the narrowest gap on record.