The Conservatives are on course for their worst election result, winning fewer than 100 seats, according to a new poll.

The seat-by-seat analysis gives the Tories 98 constituencies compared with Labour’s 468, giving Sir Keir Starmer a 286-seat majority, the Sunday Times has reported.

The 15,000-person poll, conducted by agency Survation on behalf of Best for Britain, gives Labour a 45% vote share with a 19-point lead over the Conservatives.

Rishi Sunak’s party is on track to win 98 seats with none in Scotland or Wales, according to the research. It also suggests the prime minister is at risk of losing his own constituency, the new Richmond & Northallerton seat in North Yorkshire, to Labour with his lead less than 2.5 percentage points.

The analysis forecasts that Reform UK will come second in seven seats and achieve an overall vote share of 8.5%, just behind the Liberal Democrats on 10.4%

The poll also suggests the Scottish National Party would pick up 41 seats, the Liberal Democrats 22 and Plaid Cymru two.

Naomi Smith, Best for Britain’s chief executive, said: “With the polling showing swathes of voters turning their backs on the Tories, it’s clear that this will be a change election.”

In 2019 the Conservatives had 365 seats, Labour 203, the SNP 48, the Lib Dems 11 and Plaid four.

The findings come after Labour sources said the party’s overall financial position remained strong despite membership subscriptions falling off because donations were healthy and unions were expected to give very substantial backing to the election effort.

Labour has suffered more than a 23,000 fall in membership over the past two months after controversies over its policy on Gaza and its U-turn on green investment, according to figures released to its National Executive Committee (NEC).

The party’s general secretary, David Evans, revealed that membership, which had stood at 390,000 in January, had plummeted to 366,604 at the latest count, with more than 11,700 of these being in arrears. Labour membership reached a peak at the end of 2019 when it hit more than 532,000.

Luke Akehurst, a member of the NEC, said: “Party membership is still at historically high levels. Labour only had 150,000 members at the end of its last period in office [in 2010],” he said.

“The state of the opinion polls suggest there is no correlation between membership and electoral popularity.”