Phil Coorey has a great scoop this morning about the NSW Liberal Party’s concerns about Wentworth following Malcolm Turnbull’s decision to not contest the seat at the next election.

Wentworth sits on a margin of 3.9% but a lot of that is Turnbull’s popular support from green-minded voters who were happy to support Turnbull in 2007 while vehemently disagreeing with John Howard’s record on issues like climate change.  In Turnbull’s absence, not merely have the Liberals lost their most famous candidate in the country, they’ve potentially lost a personal vote that could be the difference between losing and holding the seat later this year.

Coorey reported that Nick Farr-Jones was being considered for the seat, and that various names were being workshopped by the Liberals.  Coorey also noted that Turnbull himself was being urged to remain by some locals.

Crikey understands that senior Liberals are very concerned about being able to retain Wentworth without Turnbull.  Unlike Queensland, where an unpopular State Labor Government appears to be dragging down the Federal Labor vote, NSW voters appear to be distinguishing between State and Federal Labor, meaning that an anti-Rudd swing is unlikely to eventuate.  Without a swing to the Coalition, Wentworth minus Turnbull is in deep trouble, and will require precious campaigning resources.

Remember the Coalition starts this election even further behind than they finished the last one.  They have lost the seat of Lyne since then, and Fran Bailey’s decision to retire from McEwen will probably see that seat – the most marginal in the country – fall to Labor.  The Queensland redistribution – which forced Peter Dutton to temporarily abandon Dickson – has made the Liberal National Party’s task even harder up north.

In short, 2010 is shaping as a difficult election for the Coalition simply to hang on to what it has.  If it goes substantially backward this year, 2013 will start looking problematic as well.  They need every seat they can hang onto.

That’s one reason why Malcolm Turnbull needs to immediately reconsider his decision to retire.  He’ll hold Wentworth – hold it easily – without the need for extra campaign resources.

It’s not a reason that will appeal to Turnbull particularly.  He will feel he owes the party nothing after its treatment of him last year, and particularly given his peace offering to Tony Abbott – an offer to work under him as shadow Finance Minister – was thrown back in his face.

But there are other, compelling reasons.

Turnbull’s retirement is going to strip the party of much of its remaining substance.  Until a new generation of quality Liberal MPs makes their mark, the only real intellectual firepower in the party consists of Andrew Robb, George Brandis and Turnbull.  Yes, there are younger or more junior Liberals with some real intellectual quality – Simon Birmingham, for one – but they don’t yet have any sway within the party.

Neither Brandis nor Robb are exactly dripping with charisma, and only Robb is even faintly a serious candidate for future leadership as either Deputy or the main gig.  Turnbull’s retirement left the party with the prospect that when Abbott leads the party to defeat, Joe Hockey will be the only alternative.

As Hockey’s economic history speech this week showed, the bloke is game, but just doesn’t have the intellectual grunt.  He’d make a decent, moderate Liberal leader, in the same way Kim Beazley made a decent, moderate Labor leader.

Only Turnbull has the charisma, intellectual firepower and fierce ambition that leadership needs.

A third reason: Nick Minchin is leaving.  Minchin dedicated his last three years in politics to thwarting Turnbull.  His departure leaves the conservative forces in the party without their caporegime.  Corey Bernardi will try to step up and fill Minchin’s shoes but he is, Senator, no Nick Minchin.

A fourth reason: the Liberals know how badly they cope with opposition.  Another defeat at the hands of Rudd, especially one that sends them backwards in terms of seats, could unleash the sort of disunity that makes the last couple of years look cool and professional.  In the absence of a powerful figure, the Liberals will continue to keep the spotlight on themselves in a way that has made Kevin Rudd’s life so much easier since 2008.  There are no John Howards or Peter Costellos to unify the party now, but there nearest thing they’ve got is Malcolm.

Fifth, it can work.  Turnbull regains the leadership after the election, learns from his first stint and conquers the flaws in his personal style, provides a more consultative leadership style than the first time around, and challenges an ageing Rudd Government by offering a mix of conservative economic policies and a more progressive social agenda than Tony Abbott will ever be able to contemplate.

Because that’s the problem with Tony Abbott, or any conservative, leading the Liberals.  Such a figure might appeal to the party base, but is in constant danger of moving away from mainstream voters.  The Liberals know they face a long-term demographic challenge as one of their core constituencies, the pre-baby boom generation born before and during the war, die off.  They need to appeal to younger voters.  They need a leader who speaks to the future, not the past.

At the moment the party needs Malcolm more than he needs it. But he can still have a serious crack at fulfilling his ambitions through the party.  We all know his departure means immense talent, ambition and potential unfulfilled.

It could yet be fulfilled.  Over to you, Malcolm.