As the countdown to the EU referendum debate continues, the momentum appears to have continued to swing towards Brexit: 'Leave' went ahead in the polls last week, with one survey putting them five points clear of 'Remain'. What's more, David Cameron has looked more and more rattled. Yesterday, he had to answer questions on Marr about whether he really believed his warnings over Brexit, given that the UK leaving the European Union now doesn't seem so unlikely. So if Project Fear isn't paying off, what can the 'Remain' camp do to try and regain control of the debate? The answer for the Prime Minister this week is to take a step back from the campaign trail. Instead, Labour figures from the past and present will be urging their party's supporters not to back Brexit. Today, it's the turn of Gordon Brown. He'll say:

“ 'From now until 10pm on 23 June, we will not rest and I will not stop explaining why 9 million Labour voters have most to gain from remaining in the EU.'

So whilst Brown's enthusiasm can't be faulted, can his intervention actually help? One of the key parts of his strategy will be in putting forwards a 'positive' case for remaining in the EU. This could prove particularly powerful in reaching out to a core of Labour voters who will have been switched off by the warnings against Brexit issued by the Government. He'll also talk about an EU 'solidarity' fund for areas overwhelmed by migrants, which, at least partly, is addressing one of the key factors which could swing this debate: migration.

Brown won't be alone this week in trying to convince Labour voters of the importance of staying in: Jeremy Corbyn, Hillary Benn, Tom Watson and Harriet Harman are all hitting the campaign trail as well. Whilst Ed and David Miliband will also be trying to target voters with local newspaper articles in key Labour areas.

But is this just a desperate last-ditch attempt by the 'Remain' camp to call the substitutes off the bench? Although it might be tempting to dismiss Brown as a political has-been who won't do much to help, that would be to ignore just how crucial Labour voters will be in this vote. Whilst actual Labour members are firmly in the 'Remain' camp (some 83 per cent said they wanted to stay in the EU, according to a YouGov survey), it's the nine million Labour voters who are the ones who need to be targeted. Worryingly, many of these have had no idea what the party's position is on the EU debate. And given that around a third of people who voted for Labour in 2015 are leaning towards 'Leave', this seems particularly troubling.

This strategy by Labour to take the front foot this week, will at least address this issue then. And a show of unity over the referendum will also help to shift the referendum on June 23rd away from being a vote on David Cameron's handling of events: something that must be avoided at all costs if Labour voters are to be wooed. So can Gordon Brown win it for 'Remain'? It might sound improbable, but it's also worth remembering how crucial his intervention in the Scottish referendum was. And whilst it might have been doom and gloom for 'Remain' over the last few weeks, it's also important to consider just how many voters still change their minds in the run-up to a vote.