Leading article: Mr Cameron must listen to the call to tax the rich

The Labour leader, Ed Miliband, has come in for a good deal of criticism for his attempts to relaunch his leadership of the party with a debate on the need for a kinder, more responsible form of capitalism. Cut the deep philosophising and get on with hammering the Coalition Government more effectively, is the caustic response of some on his own side.

The broad charge of critics of the Lord Glasman variety – which is that Mr Miliband is being too intellectual and donnish for the stomachs of most voters – may have weight. Certainly, his poll ratings continue to languish.

But Mr Miliband can rightly respond that, if imitation is anything to judge by, his arguments are getting under the skins of the Coalition leaders. Significantly, both the Deputy Prime Minister, Nick Clegg, and the Prime Minister, David Cameron, are delivering their own responses this week to some of the ideas posed by Mr Miliband on the need to curb what he terms "irresponsible" or "crony capitalism".

Today, for example, the Deputy Prime Minister will make a call for millions of workers to be allowed to own shares in their companies along the lines of the partnership model at John Lewis. Meanwhile, ahead of the next Budget on 21 March, he and his Liberal Democrat colleagues are setting out a platform based on a demand for tougher taxes on the rich to match the growing misery being visited on the low paid. These include a mansion tax on owners of homes worth more than £2m, abolition of the 40 per cent tax relief on pension contributions for higher-rate taxpayers and a squeeze on "non-domiciles", foreign residents living in Britain who do not pay tax on overseas earnings.

If these were "normal" political times, the Conservatives might be tempted to dismiss the Liberal Democrats' raft of tax-the-rich proposals as little more than a crude attempt to grab the headlines and reclaim voters lost at the time of the tuition fees row by picking a fight with the Tories. But the times are anything but. As cuts bite deep into ordinary people's wage packets – poor retail figures over Christmas provided fresh evidence of that – and as the economy remains stuck in the doldrums, many Tories are just as aware as the Liberal Democrats of the danger of being seen as a hatchet-faced government of the well-off.

The Tories are also sensible of the dangers of allowing a debate on "crony capitalism" to gather momentum in the country and slide into the sole ownership of the Labour Party, which is why they want to grab part-control of the argument by putting forward markers of their own. This is the reason Mr Cameron will be making his speech on the acceptable face of capitalism on Thursday, although unsurprisingly he will strike a different note to that of Clegg and Miliband, concentrating more on the merits than the failings of the free market.

The question is how, and whether, the Conservatives can respond to Liberal Democrat, and indeed Labour, calls for the rich to shoulder a greater burden of the economic pain without appearing to be dragged along by them. Debates on the merits of the capitalist system – a given for most Tory MPs – are not natural political terrain for the Conservative Party, which once felt content to state the case for a free market with no ifs and buts.

But Mr Cameron now has no option but to present a Tory argument for capitalism in new, subtler colours. Public opinion is shifting as support for Tory-led cuts dwindles in the face of stubbornly depressing data. The Prime Minister must take the initiative by making it clear he understands the need for a "fairness agenda". If he fails to do so, he risks handing his opponents in the Labour Party, not to mention the Liberal Democrats, an issue that they will certainly run with in the next election.