Initial reactions to Ed Miliband’s Labour conference speech have been overwhelmingly positive, with even Tories praising the delivery, if not the content. And it really was an excellent conference speech – by far Miliband's best, potently argued without over-doing the wonkish language.
It was a speech that signalled the birth of "One Nation Labour"– a potentially election-winning concept. While Miliband didn’t deliver any new policy announcements, the theme of unity is well-judged for the current climate. It also fits neatly with Labour attacks on Conservatives as elitist and out-of-touch, and criticisms of David Cameron for failing to govern in the inclusive manner he promised. So far, so promising.
But the life of "One Nation Labour" will not be without its challenges. Here are a few that it will have to successfully overcome if it is to secure the party a majority in 2015.
1. ‘New Labour in disguise’
The most obvious Tory attack line will be to remind voters of New Labour and argue that "One Nation Labour" merely amounts to the same ideas in a new disguise.
Miliband has said before that "the era of New Labour has passed". But a new catchphrase for the party, appealing as it may be, will meet with cynicism from the millions of voters for whom "New Labour" merely equates to dashed dreams.
2. Who does One Nation Labour speak for?
One of the curious aspects of Miliband’s speech was that, while it was delivered in decidedly centrist terms, its concrete policy content did not reflect that. To put it another way, this speech would have been viewed as a lurch to the left had it lacked the "One Nation" theme. The stern words about immigration were pure Blue Labour. And on education and health, Miliband’s trenchant criticisms of the current government’s policies were, by extension, rejections of New Labour’s reforms too. With this Parliament not quite yet into its second half, there is ample time for him to deal with these issues. But the crux of his problem is that as the election nears, the double act of pleasing the left with policy announcements, while speaking in rhetoric aimed at winning over swing voters will no longer be viable.
3. Committing too soon?
Although Miliband has been shy of making concrete policy commitments, he risks future policy being hemmed in by his criticisms of the current government.
Take the 50% tax rate and the NHS. While his opposition to the government’s policies in these areas has broad appeal, it would be easy to believe that Labour have made concrete promises to restore the 50% tax in 2015 and repealing the NHS bill – neither of which are true. In the case of the NHS bill, this may simply not be viable by 2015; indeed, repealing the bill on account of its expensive and top-heavy nature would require more expensive and top-heavy policies.
4. That crowded centre ground
Taking the speech on its ‘One Nation’ theme, this was a plea for the centre ground. But, even if it was successful in helping to establish Cameron’s Conservative Party as not being of that centre, Labour face other challenges for it.
Nick Clegg’s former director of strategy Richard Reeves recently argued  that “the left-wing votes 'borrowed' from Labour in 2010 will not be available in 2015" and, accordingly, that the Lib Dems should focus on making themselves the party of the "radical centre". The trouble for Miliband is that such a political space seems little different from his own "One Nation" theme. And predictions of Lib Dem wipeout have become less fashionable, recognising both the party’s long history of defying grim circumstances and, more importantly, the immense personal popularity of many of its 57 MPs. It will be very difficult for Miliband to make inroads into the 57 – as he must – without offending some of his own core support.