Labour and Lib Dem cooperation key to defeating Tories at by-elections, top polling guru says

Prof John Curtice says Tory candidates could cling on if parties insist on splitting vote

Ed Davey and Keir Starmer have denied working together informally (Getty)

Cooperation between Labour and the Liberal Democrats could be key to defeating Rishi Sunak’s Conservatives in a slate of upcoming by-elections, a top political scientist has said.

Sir John Curtice said tactical voting would be crucial in the seats up for grabs after Boris Johnson and two other Tory MPs quit the Commons.

Mr Sunak is facing three difficult electoral tests in Mr Johnson's former West London seat of Uxbridge and West Ruislip, as well as in the constituencies of Mid-Bedfordshire and Selby and Ainsty.

These contests were triggered after MPs Nadine Dorries and Nigel Adams, both allies for the former PM, follow him out of the door after a row over whether they would get seats in the House of Lords.

Writing in The Independent Sir John, a highly respected professor of politics at the University of Strathclyde, suggested that all seats were potentially within grasp of opposition parties under the right conditions.

But he said previous experience of by-elections showed that in that Mid-Bedforshire especially, opposition prospects could hang on whether Labour decided to mount a serious campaign – or leave the Lib Dems to hoover up tactical votes.

“The Liberal Democrats would need as much as a 24-point swing to take the seat from the Conservatives. But that is less than the 34% swing the party secured in North Shropshire and the 30% swing in Tiverton & Honiton,” he said, referencing two recent by-election upsets pulled off by Sir Ed Davey’s party.

“However, one key ingredient of those Liberal Democrat successes was the party’s ability to persuade Labour voters to cast an anti-Conservative tactical vote in their favour – in both instances the Labour vote fell heavily.

“That squeeze was seemingly aided by Labour’s apparent decision not to mount much of a campaign in the seat, a decision that was reciprocated by the Liberal Democrats in the Wakefield by-election where Labour emerged victors.”

Boris Johnson’s Uxbridge seat ‘essential’ for Labour, says Prof John Curtice (N/A)

Sir John questioned whether Labour would be willing to take this approach this time around given the wider political context of a looming general election.

The top political scientist said that in Uxbridge and West Ruislip, Labour would have the best change of beating the Conservatives – and that victory “would seem not just a desirable but an essential target for Sir Keir Starmer” were he on course to win a general election.

In Selby, Sir John said Labour has previously enjoyed “enjoyed significant support there in the past” – though it would need an 18 per cent swing against the Tories to win.

Tory peer Lord Hayward told The Independent the byelections will be “serious challenge for the Tories” to win. “It’s very difficult for a government to win byelections, even if they have large majorities.”

The elections expert warned Sir Keir Starmer that the contests are also a big challenge for Labour. “They have to do well to prove they are ready to get the votes they need in some very different constituencies.”

Despite the prospect of awkward campaigns ahead, Lord Hayward said Mr Sunak would be relieved to have Mr Johnson and some of his staunchest supporters gone.

Rishi Sunak will be relieved to see Boris gone, says top Tory pollster (AFP/Getty)

“Despite the short-term, problematic by-elections, Rishi avoids longer-term problems. Boris is big personality – he still enormous potential to cause problems. But on balance, it’s cleaner for Rishi to have Boris and those allies outside parliament”

The senior Tory figure added: “I think Rishi Sunak has dodged a bullet. If Boris had fought the byelection, it would have been mayhem – a really divisive thing for the party, with some going to campaign for him and others not supporting. What would Rishi have done?”

No date has yet been set for the by-elections, with the timing reliant on when the government choses to “move the writ” in parliament. But the votes are expected within three to four weeks.

Opposition parties have however wasted no time in starting their campaigns, with senior Labour figures including campaign coordinator Shabana Mahmood hitting the doorsteps in Uxbridge and West Ruislip over the weekend.

Lib Dem leader Sir Ed meanwhile meanwhile travelled to Mid Bedfordshire on Monday to declare the constituency “a close race” between his outfit and an “out of touch” Tory Party.

Speaking on Monday communities secretary Michael Gove said by-elections are always “challenging”, but added: “Elections are part of political life.”