An Ipsos poll put support for the Conservatives, in power for 14 years, at 20% at the end of February, down seven percentage points in a month, with the opposition Labour Party on 47%.

It was the lowest support Ipsos had recorded for the Conservatives since at least 1978, when it began regularly tracking support for the main parties.

The previous low was 22% in 1994, when John Major was Conservative prime minister, three years before the party suffered its heaviest electoral defeat in almost a century.

“The historical comparisons continue to look ominous for Rishi Sunak and the Conservatives,” said Gideon Skinner, head of political research at Ipsos.

Prime Minister Rishi Sunak has said he expects to call a general election in the second half of this year, but has not given a date.

For the poll, Ipsos interviewed 1,004 adults in Britain by phone between Feb 21 and 28.

The slump in Conservative support follows a difficult start to the year for Sunak, with the news that Britain entered a recession at the end of last year.

Paul Scully, a former technology minister, was the latest Conservative to announce he would leave parliament at the election.

“Fuelled by division, the party has lost its way,” he said. “It needs a vision beyond crisis management which can appeal to a wider section of the electorate.”