David Shearer's education policy speech earlier this month may have had at least some of the hallmarks of a pitch for the political centre, but at its heart was an appeal to Labour's rank and file.

Not that this was obvious. His implied critique of the failure of the education system for lower decile pupils and push for reading recovery will certainly resonate with many outside Labour's base, but at the potential cost of support from teachers' unions. By the same token his softening on National Standards also reflects what his focus groups will have been telling him - parents are on side with them even if educators are not.

But the proposition that the State begin feeding the children of lower decile schools goes right to Labour's heartland. There might be vestiges of support to be clawed back from the liberal middle class, but only on the assumption of a sustained lack of analysis concerning the perverse incentives and threats to the integrity of the welfare system inherent in the idea. No, this one had nothing to do with reaching out for new supporters; it was aimed entirely at the troops.

This focus has become a regular if not routine underpinning of Shearer's recent speeches. One of several on the theme of social health, equity and equality, these policy statements have less to do with political evangelism than with an appeal to an existing base. And the big question posed by this is why?

The answer lies in the continued insecurity of Shearer's leadership and the need to build sufficient cushion to see off any challenge by the most likely contender, David Cunliffe.

Cunliffe, positioning to Shearer's left and building his own constituency with Labour's base cannot afford to wait forever. If he is going to move he will need to do so soon. Heading that off has to be a priority for Shearer if he is to survive into the latter half of next year

To that extent Shearer can be well pleased with his education speech. It will have struck a chord with Labour activists and gone some way to offsetting the advantage that Cunliffe has built up by his aggressive Parliamentary performance and easier command of the media. The hill in front of Cunliffe's aspirations just got a little bit steeper.

Until Labour's leadership wrangles are resolved once and for all, making that hill as steep as possible will remain Shearer's principal goal. Consolidation not expansion can therefore be expected to be the flavour of his policy speeches over the short and medium term, putting at risk Shearer's capacity to bid for fresh support and distracting him from the real prize in 2014.

But even if his eye stays on the bigger game, Shearer will have few places to go in his bid for an election win. The most likely will be an appeal to last election's non-voters on the assumption that they were Labour Party "no shows".

Here an astute alignment of giveaways with Labour's brand of social justice may give Shearer the cushion he needs for the longer term. But it will remain a risky strategy and one difficult to sustain in the face of the wider constituency's preoccupation with responsible economic and fiscal management. Lunches will serve a purpose, but they will not come free.