“I’M ENJOYING every minute of this election!” declares Jeremy Corbyn at the end of the stump speech that he has been making at rallies around the country. Coming from a politician who became leader of his party almost by accident in 2015 and is tormented mercilessly by the press, the claim has sometimes rung hollow. But with just a week left until polling day, it is sounding more convincing.

Written off by the pollsters and dismissed by his opponents when Theresa May called the election in April, Mr Corbyn and his Labour Party have seen a surge in their support in the past two weeks. The Conservatives’ average lead has fallen from nearly 19 points in April to six. It amounts to one of the steepest swoons in four decades of elections (see charts).

The Corbyn camp is elated. Not only are they giving the Tories a fright, they are proving to their Blairite opponents in the Labour Party that a far-left programme need not flop. Even some of Mr Corbyn’s staunchest detractors concede that he has run a good tactical campaign, shifting the agenda off leadership and Brexit—the ground on which the Tories are strongest—and onto public services such as schools and hospitals, safe Labour territory.

He has been helped by some bad missteps by Mrs May. Her U-turn on a plan to fund social care for the elderly, four days after it was heralded as the centrepiece of the Conservative manifesto, turned her slogan of “strong and stable leadership” into a punchline. Her few unscripted public appearances have been underwhelming. On May 31st she was pilloried for being the only party leader not to take part in a televised debate, sending her home secretary, Amber Rudd, instead.

Mr Corbyn, by contrast, has tended to exceed the rock-bottom expectations that most voters have of him. This is important, argues Robert Ford of Manchester University, because for moderate Labour supporters who might have abstained in protest at Mr Corbyn’s far-left agenda, he is no longer such a “deal-breaker”. Ruth Cadbury, a Labour MP defending a thin majority in the west London seat of Brentford and Isleworth (who voted to oust Mr Corbyn as leader last year), says that on the doorstep people say he is “not the bogeyman portrayed in most of the press…that he’s fair and principled.”

The strengths and weaknesses of the Labour campaign can be seen at Mr Corbyn’s rallies. Part rave, part agitprop, they draw in thousands. The crowd is warmed up with dance music; the enemies of the people—mainly bankers and the “mainstream media”—are ritually booed; and then Mr Corbyn recites a list of promises of how under his Labour government the state will pay generously for the public services that the Tories want to starve. This draws a crescendo of cheers.

Mr Corbyn’s team argues that these rallies, together with the aggressive use of social media, are the only way that their man can bypass the biased media and deliver his unfiltered message to voters. Bernie Sanders, a left-wing senator who ran against Hillary Clinton for last year’s Democratic Party presidential nomination, is invoked as a model.

But take a closer look at a Corbyn rally and its limits are apparent. The crowd is mainly young; much of Labour’s recent surge comes from a rise in support among young voters, from an average of 43% in mid-April to 57% now. The snag is that they may not vote in the numbers expected by some pollsters (see article). Backing among the elderly, who turn out like clockwork, has risen by just four points, to 19%. “I will take the surge seriously if Labour’s doing better with the over-65s,” says Andrew Harrop, head of the Fabian Society, a centrist Labour think-tank.

Furthermore, most Corbyn rallies take place in solid Labour seats, where the leader preaches to the converted. There is little evidence of the campaign attempting to persuade Conservative voters to change sides; most of the effort is going into minimising losses. By contrast, the Tories are invading Labour turf (see Bagehot).

Nonetheless, Mr Corbyn looks on course at least to achieve two things that were in doubt a month ago. If his poll numbers hold up, he is likely to deny Mrs May the landslide that she must have hoped for when she called the election. A slimmer majority would embolden Tories who disagree with her brand of Conservatism—and there are plenty of them—to grumble more loudly. Opposition to her Brexit plan may be stronger, from both Remainers and her own hardline Eurosceptics.

Second, Mr Corbyn is better placed for the battle after the election if Labour loses. Labour centrists have long wanted rid of him. His supporters say his case for staying on, or nominating a like-minded successor, will be stronger if he exceeds the 30% share of the vote achieved in 2015 by Labour’s previous leader, Ed Miliband (never mind if Mr Corbyn wins fewer seats). Richard Angell, head of Progress, a moderate Labour pressure-group, acknowledges that members “are going to rally around him. They’ve had a shot in the arm.”

It is depressing that the prospect of a higher vote-share than in the disastrous 2015 election is enough to inspire such excitement. If Mr Corbyn has succeeded in one thing, it is managing expectations.