Has the past fortnight underlined the challenge for Brown and Cameron?

The mathematics of the next general election are straightforward – there are more votes to be gained by appealing to the centre ground in British politics than anywhere else.

The Tories need to be winning back the voters who moved to the Lib Dems and Labour during the 1990s. The objectives for Brown’s party, meanwhile, are to get back the 6-7% of the national vote share that moved to the Lib Dems in 2005 and the 3-4% that the polls suggest has gone to the Tories.

Yet for both leaders, as we have seen in the past fortnight, doing this might be tougher than it appears for they have their base supporters to consider.

In a thoughtful main leader this morning the Independent looks at the messages that have been coming from some of Labour’s deputy leadership candidates and the tensions that the Tory party has gone through with the grammar school row.

It goes on: “Inevitably, the Tory rebellion and the outbreak of candour from some deputy leadership candidates embarrass the leaderships of both parties. But the causes of the leaders’ anguish can be healthy for the wider political culture. The fashion for political cross-dressing, as Mr Blair has misleadingly described the current political era, can lead to apathy among the electorate. Over the past few days, voters who protest that “the parties are all the same” have discovered that the parties of the left and right are capable of distinctive passion. In an era where the media focus is almost exclusively on the leaders, giving the false impression of a presidential contest, the parties have shown the limits of a single person’s power.”

For Labour the problems is not about votes seeping off to the far-left but simply motivating those voters who are Labour supporters to actually bother to go to the polls. Cameron does have a marginal problem with UKIP and on the right but in general elections the anti-EU party is going to be hard pressed to get more than a couple of per cent and not all of that will be from the Tories.

So maybe we have been seeing the limits of the push to the centre. Maybe things might not be as gloomy for the Lib Dems as recent polls have suggested?

The Labour deputy leader betting still has Hilary Benn as the strong favourite

Mike Smithson