Tony Blair needs the clash of genuine debate if he is to rejuvenate his party

Even Tony Blair's enemies would accept that he has got a nightmarishly crowded in-tray. At the best of times his job is a demanding one. Now some of Mr Blair's friends seek to make his in-tray even more crowded. As The Independent reveals today, the Fabian Society is calling on him drastically to revise his party's constitution. The Fabians are being more emotive than that. They seek a new Clause 4 of the party's constitution, arguing that the current version, famously drafted by Tony Blair soon after he first became leader, is out of date.

Even Tony Blair's enemies would accept that he has got a nightmarishly crowded in-tray. At the best of times his job is a demanding one. Now some of Mr Blair's friends seek to make his in-tray even more crowded. As The Independent reveals today, the Fabian Society is calling on him drastically to revise his party's constitution. The Fabians are being more emotive than that. They seek a new Clause 4 of the party's constitution, arguing that the current version, famously drafted by Tony Blair soon after he first became leader, is out of date.

On the surface, it appears as if the serious-minded Fabian Society is out to make mischief, the equivalent of a teetotaller enjoying a night on the town. Ten years ago, the battle over Clause 4 defined Mr Blair as a political leader. Where former Labour leaders had dithered, he made the symbolic change. Once he had won the battle, he argued that Labour was indeed new, with a revised constitution to prove it.

In the autumn Fabian Review, to be published shortly, the society's research director, Richard Brook, argues that the removal of the old Clause 4 was a significant achievement, but that its Blairite replacement is now inadequate. "There is little in the Labour Party's statement of values," he writes, "that is seriously objectionable to anyone from the mainstream of British politics. Many Labour Party members cannot identify enthusiastically with the new Clause 4 because it misses out key elements of what makes politics important to them."

In particular, the Fabians argue, there should be a new emphasis on tackling inequality and a clearer stance on international affairs in the light of recent events such as the war against Iraq.

Unlike other left-of-centre think tanks, the Fabians are formally affiliated to the Labour Party. When they stir, something is going on. The current general secretary, Sunder Katwala, is broadly an admirer of Tony Blair, not one of those engaged in the Whitehall power battles that are d raining much ministerial energy. Yesterday he told me that the Fabians were not merely proposing a new Clause 4 as a clever device to start a debate about the future of the Labour Party and the Government. They seek a pre-election debate about a new constitution and then some practical changes once the election is out of the way. They are still serious-minded. They want a new Clause 4.

On one level, Mr Blair needs a new internal debate about the entire purpose of his party as much as another set of front pages speculating about his future. There is almost something darkly comical in the notion that this might be a constructive intervention: "Prime Minister, Iraq is imploding, there are no weapons, the Chancellor is fuming about the reshuffle - why don't we have a new debate about Clause 4?"

Even so, this is meant to be a constructive intervention, and might prove to be one. The Fabians are good at being ahead of the game. They led the way in arguing for tax rises linked to improvements in public services. It was their tax commission that preceded Gordon Brown's Budget in 2002, the one that put up taxes to pay for improvements in the National Health Service. Once more the Fabians are on to something, and in a way that chimes with some of the concerns articulated by leading Blairites.

They make the powerful point that a party can only thrive when there are clear ideological boundaries. In other words, a constitution for a party must contain elements that quite a lot of voters would disagree with. The Clause 4 debate instigated by Mr Blair 10 years ago took place in a very different political context. Labour had lost four elections in a row. It would do almost anything to win. The prospect of victory was enough to enthuse the growing army of excited activists.

After two landslide wins and seven years in government, the mood is very different. As the leading Blairite, Stephen Byers, has argued in recent days, one of the challenges for the leadership is to engage with the rapidly declining number of Labour Party members. This is what the Fabians are trying to do. I am told that several Blairite ministers have indicated their support for the initiative.

This should not be altogether surprising. Mr Blair and others associated with New Labour have always been interested in ideas and guiding philosophies in spite of their highly developed pragmatism. In ways that are not fully recognised, Blair and Brown - sometimes working together, increasingly working apart - have fleshed out what Neil Kinnock first described in the mid 1980s as the "enabling state", a new relationship between the Government and those it seeks to help. This is an active state, but one that is very different from the stifling corporatism of the 1970s.

Examples of an enabling state include welfare to work, the focus on extensive childcare facilities, and the encouragement of new flexible working arrangements, a policy that is soon to be extended further by the Trade and Industry Secretary, Patricia Hewitt. In Downing Street there is much focus on this theme as work on the election manifesto is intensified.

Perhaps a new internal debate would encourage Mr Blair to put the case for the enabling state more openly. He tends to emphasise the importance of the private sector in the provision of public services in a way that arouses a neurotic response from many on his own side. Quite often he is proposing more modest proposals for the private sector than those already in place in countries such as Sweden where there is a much stronger social democratic tradition.

The difference is that in Britain, after the failures of corporatism and the anti-state oratory of Thatcherism, there is justifiable confusion about the role of the state. We await a big prime ministerial speech on the enabling state rather than one that highlights provocatively the importance of the private sector.

Admittedly, the Fabians raise more thorny issues. They want equality - more precisely the inequality gap - to be at the heart of the new debate. Such a debate would move to the related issue of taxation. In the Treasury they agonise over inequality, aware that its policies have failed to help some of those in poverty. But Gordon Brown's instincts on income tax, at least in terms of the electoral implications, are close to Mr Blair's. They regard it as politically impossible to act. Still, the Fabians stride on to this terrain with good cause. Tax cannot remain a political taboo for much longer. The Chancellor is already in the contradictory position of being famous for taxing stealthily.

In 1991, when the Tory government was being bashed around on several fronts, Nigel Lawson predicted his party would win the next election because it was still winning the battle of ideas. A year or so later, the Conservatives secured an easy victory. Now the more fertile debates whirl around the future of a Labour government. Tony Blair should regard it as a sign of strength that he is being asked to fight another battle over his party's constitution.

s.richards@independent.co.uk