By Friday, Labour's campaign chief Douglas Alexander may be Britain's foreign secretary. Or he may be jobless, beaten by a 20-year-old Scottish Nationalist undergraduate.
But a month ago when Mr Alexander opened a new campaign office in his constituency of Paisley and Renfrewshire South, well over a hundred helpers turned up on a weekday afternoon to applaud their man and put their names down for routine election jobs.
Even then it was clear that the Labour candidate was in trouble, and normally defeats of such magnitude are orphans. However, in Paisley and across Britain, there has been an unusual vibrancy around the party's local constituency offices, unseen since 1997.
Not the intensity that is driving the SNP nor the starry-eyed innocence of the Greens, but a zest and diligence emanating largely from a generation too young to vote 18 years ago, harnessed to achieve the party's target of 5 million doorstep conversations with voters.
In London's northern suburbs, Labour plans to flood the marginal seat of Hornsey and Wood Green with 1,600 activists on Thursday - part of an effort dubbed "GOTV" - Get Out The Vote.
The party is already confident of achieving victory in up to 25 constituencies including former Lib Dem seats such as Manchester Withington and Brent Central.
It is now pouring resources in the final few days of the campaign into another tier of 20-25 target seats where polls show the parties are neck-and-neck. These include Pudsey, Northampton North, Vale of Glamorgan, Loughborough, Wirral West and Nuneaton.
At least 500 activists will visit each of those target seats on election day in a major final push. Every household there has already been sent up to 20 leaflets in the past three months. Now voters will be told they are running out of time to achieve a change in government: “Vote Labour and save the NHS,” will be a key message.
Upper hand
The party believes it has the upper hand in the face-to-face “ground war”, fought street by street in the most marginal constituencies.
Mr Alexander claims a “superior” ground operation to the Conservatives - with 300 paid activists in the 106 targets for at least a year before the election.
The Labour campaign chief has a chart on the wall monitoring Labour’s 5 million face-to-face conversations target, which has now almost been achieved.
Evidence shows that knocking on doors increases the probability that someone will actually go and vote for you on the day.
Senior figures take heart from polling by Tory peer Lord Ashcroft which suggests that the "contact rate" - the number of voters who have encountered a party activist - is much higher for Labour than the Conservatives.
"Everyone in our marginal seats has heard from us several times because we've delivered them literature, but what matters is what people remember receiving," says Lucy Powell, who runs the day-to-day campaign. "It's about the quality of those contacts and that can't just be pamphlets. It has to be conversations."
With Scotland now largely a lost cause for Labour, the party’s best hope of victory on Thursday is to harvest large numbers of seats in the southeast, the Midlands and the northwest, mainly from the Conservatives.
Information from activists in marginals such as Hornsey and Wood Green is fed into Labour’s specialist software, called “Contact Creator”, which stores a vast database of names and propensity to vote for the party. It can tell the party the names of perhaps 20,000 likely supporters in any given constituency.
European data protection regulations constrain British parties from the micro-targeting of voters common in US elections - where parties can buy data from commercial brokers. But Labour’s data operation is more sophisticated than in previous elections.
Prospective voters
Contact Creator includes all sorts of information about prospective voters including when they are likely to be at home - enabling an “hour-by-hour plan” for activists on Thursday. The party uses the software - built by information services group Experian - to ensure it deploys activists to canvas when and where it is most effective.
Sadiq Khan, who is running Labour's campaign in London, says door-knocking is no longer about "persuasion" at this point in the campaign.
“Evidence shows that knocking on doors increases the probability that someone will actually go and vote for you on the day,” he says during a pause in campaigning. Labour believes that getting the turnout up from 60 per cent to 70 per cent in critical constituencies could make all the difference.
Senior figures in the party say that Contact Creator played a crucial role in reducing the swing away from the party in 2010 in some of the most important seats. Not only does it identify potential supporters - and those who will never vote Labour - but also people’s biggest concerns: they can then be blitzed with tailor-made messages.
In Watford, Labour candidate Matt Turmaine uses Contact Creator to focus conversations with constituents on issues they're interested in. "It's an essential thing to do because it enables us to focus what we talk to them about... we record notes on conversations so we can make sure we're not wasting our time and we're not wasting their time," he says.
Ed Miliband will spend the last few days of the campaign emphasising his message about the NHS and framing the contest as a “choice between two visions”.
The leader moved his parliamentary team across to Brewers Green, Labour’s HQ in Victoria, early in the campaign - taking up some space formerly occupied by Rolls-Royce. There are now 250 Labour staffers in the building.
Throughout the campaign eight key figures have gathered each day around a large table, including Mr Miliband, Mr Alexander and Ms Powell. They are deputy leader Harriet Harman, shadow chancellor Ed Balls, director of strategy Greg Beales, chief of staff Tim Livesey and campaign director Spencer Livermore.
Ahead of polling day the MPs in the core circle are spending more time in their own constituencies - especially Mr Alexander in his Scottish constituency.
In depth
An initial meeting of Mr Miliband’s closest advisers begins at 7.45am, followed by a second 8am meeting with the wider group - and then another at 3pm. Many staff in Brewers Green work until the end of the BBC news at 10.30pm, with some staying beyond midnight.
David Axelrod, the former Obama adviser, arrived in London last week; but his input for the past year has been to hone Labour's "strategic" message rather than advise on data or internet campaigning.
The latter is run by Kat Segal, head of digital, who co-ordinates YouTube videos, Facebook and Twitter - including a "Thunderclap" technique where thousands of supporters put out the same message simultaneously. Some 1.7m people used a Labour app celebrating the NHS's 66th birthday.
Labour has attracted more than 149,000 donations during the campaign, crowdfunding more than £2.7m. “We are applying many of the lessons from the Obama campaign, albeit with a very British twist,” says Mr Alexander. “I don’t think they ever sold tea towels.”
Matthew McGregor, a director at Blue State Digital - an agency owned by WPP - is advising Labour on its digital techniques. He says that social media is at its most powerful in recruiting supporters and then - ironically - “motivating them to turn off their computers.”
As Mr Alexander puts it: “We’re using cutting-edge technology to do more traditional campaigning and to do it better.”
Financial Times