Sir John Curtice: The "Burnham bounce" is real but it's not massive

The consistent message of the opinion polls since the new prime minister walked into Downing Street almost a fortnight ago is that Labour is enjoying a "Burnham bounce". And this has now been confirmed by the party's convincing victory in Thursday's Greater Manchester Mayoral by-election.

Polls conducted in the last week put Labour on average in the mid 20s. It is the party's highest standing since the beginning of last year and compares to their rating of 19% in late June when Sir Keir Starmer announced he was standing down.

But with Reform polling only narrowly behind Labour, Burnham's party still has a long way to go before it can face the prospect of fighting a general election with confidence.

The Burnham boost is far from unprecedented.

All but one of the recent mid-term changes of prime minister have been followed by an increase in the popularity of the incumbent government. Support for Labour rose by seven points after Gordon Brown replaced Tony Blair in 2007, while the Conservatives enjoyed a six-point bounce when Boris Johnson took over from Theresa May in 2019. Only Liz Truss' arrival in Downing Street in 2022 – which was overshadowed by the death shortly thereafter of Queen Elizabeth II – failed to give her party a boost.

We should also bear in mind the depth of the electoral hole that Burnham has inherited as Labour leader. The 19% at which Labour stood when Sir Keir resigned was the lowest poll rating passed on by any prime minister departing mid-term – even lower than the 23% bequeathed by Liz Truss when she resigned after just 45 days in office.

Against that backdrop, it would have been very surprising indeed if the replacement of the deeply unpopular Sir Keir by the relatively popular Burnham had not given Labour a short-term boost. However, even after Mr Burnham's bounce, his party's poll average is still the lowest for any newly minted mid-term PM, while the party is still well adrift in the polls of the (relatively low) 35% it won at the 2024 general election.

That said, Labour's victory in Thursday's Manchester Mayoral by-election was convincing. True, Labour's 47% share of the first preference vote was well down on the 63% that Andy Burnham secured in the last mayoral contest shortly before the 2024 general election. However, not only did it represent a near doubling of the 24% that Labour registered across the region in May's local elections, but also it was even four points up on Labour's tally locally in the 2024 general election – and thus a much better performance than would have been anticipated from even the latest national polling.

But with still no more than a narrow lead over Reform, it is unsurprising Burnham has ruled out an early election. In any event, Reform's displacement from first place in the polls for the first time in over a year appears to owe more to its own difficulties than it does to Labour's new-found popularity.

Reform has been dogged in recent weeks by questions about the legality of the source of some of its funding and about whether Farage should have declared to the Commons' authorities some of the funding he received before being elected an MP. Following these allegations, Farage announced on 7 July that he was standing down and putting himself again before the voters of his Clacton constituency in a by-election now scheduled for 13 August.

This move appears to have backfired. Immediately before Farage's announcement, Reform's average poll rating stood at 27%. In the polls conducted immediately after Farage's announcement, it fell by three points to 24%, the level at which it still stands now, and the lowest it has been for 15 months. At the same time, Farage's personal poll ratings are now the worst they have been since he returned as Reform's leader during the 2024 election campaign.

In the Manchester by-election, Reform's share of the first preference vote was nine point down on its tally across the region in May's local elections. As in the Makerfield by-election, the party seemingly suffered from the advance made by Rupert Lowe's breakaway from Reform, Restore Britain, who won nearly 9% of the Manchester vote, outpolling the Conservatives in the process.

But for Reform's difficulties, the "Burnham bounce" would probably have been insufficient to put Labour in the lead in the national polls.

The principal source of that bounce has been clawing voters back from the Greens and the Liberal Democrats, both of whom have suffered a two-point drop since Burnham's uncontested victory in the Labour leadership contest. For the Greens – much of whose increased support in recent months came from disappointed 2024 Labour voters – the change of prime minister has proven particularly damaging. The Greens' current 11% tally is as much as four points adrift of where it was when Sir Keir announced he was leaving.

When he resigned, 14% of Labour's 2024 election voters said they would now back the Greens. That figure is now 9%.

Winning back former Labour voters has generally been a key component of the Burnham bounce. Overall, 67% of those who voted Labour in 2024 now say they would vote for the party, compared to 57% when Sir Keir indicated he was leaving Downing Street.

Following Farage's difficulties, Labour is also now losing fewer of its 2024 voters to Reform. But the same is true of the Conservatives, whose loss of support to Reform in the polls during in this parliament has always been much greater than that suffered by Labour. Far from suffering from a Burnham bounce, Kemi Badenoch's party has edged up to 20% in the polls for the first time since last spring.

Burnham's arrival has given Labour new hope. But despite having overtaken Reform in the polls, the new Labour leader still has to prove he can win back the working class pro-Brexit voters that Labour once regarded as its core vote but who now form the heart of support for Reform.

To do this – and put Labour on course for victory in 2029 - Burnham needs to deliver on the policy challenges facing his government, which remain as formidable as those that beset Sir Keir. Labour's prospects at the next election will ultimately depend on whether voters have come to believe that what he has said he will do is actually happening.

John Curtice is Professor of Politics, Strathclyde University, and Senior Fellow, National Centre for Social Research and The UK in a Changing Europe

Top picture credit: Reuters

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