Mr Koizumi will have to tread a delicate path, taking care not to alienate too many of the party's traditional supporters, but at the same time appealing to a broader electorate

If it had been left to the LDP hierarchy, Mr Koizumi would never have got the job.

But faced with the massive wave of support he got from ordinary party members, they had no choice but to bow to the inevitable.

Ironically, Mr Koizumi's victory came about almost certainly as a result of one of the big corruption scandals that have rocked the party in recent years.

Double challenge

What happened was that secret payments to a leading politician, now under arrest on charges of taking bribes, were disguised as membership fees for thousands of people, who were enrolled as members of the LDP without their knowledge.

The party had no way of knowing who were genuine members, so when the ballots went out to the rank and file, the "ghost members" got them too. Some even got more than one ballot.

The new PM warns of economic changes ahead

So Mr Koizumi faces a double challenge.

He is not the politicians' first choice, but the public have given him a massive vote of confidence - and expectations are riding high on him being able to deliver the solutions to Japan's deeply ingrained problems.

To make a British comparison, the task facing Junichiro Koizumi is similar to that faced by Tony Blair when he took on leadership of the Labour Party.

The LDP is wedded to a whole range of ideas out of step with the fast-moving, global economy - support for inefficient farmers, over-reliance on grandiose public works, and above all, jobs for the boys - contracts handed out on the basis of personal favours, rather than the best candidate for the job.

Reform pledge

Like Tony Blair, Mr Koizumi will have to tread a delicate path, taking care not to alienate too many of the party's traditional supporters, but at the same time appealing to a broader electorate.

Ordinary voters have become so disillusioned with politicians of all parties - not just the LDP - that they have elected a string of independent regional governors with no affiliation to any party.

Voters have become disillusioned

As a result, Mr Koizumi has pledged to reform the whole political process.

The first sign of how much this promise is worth will come when he chooses his cabinet.

In the past, jobs have always been allocated on strict rotation among party factions, and rarely with any regard to genuine ability.

The LDP has no coherent political philosophy, other than a vague commitment to conservative principles.

It is an extremely loose coalition of politicians brought together through personal allegiances, often with deeply conflicting views on policy.

Mr Koizumi's job is to change all that.

Catalyst

It is a tough task, but there has been talk in Japan for the past eight years about the need for a complete realignment of parties on clear policy lines.

Mr Koizumi's election may just prove to be the catalyst to bring that about.

One way he may achieve it is by tying up with like-minded reformers in the opposition Democratic Party, maybe not immediately, but when it comes to getting difficult legislation through parliament.

He has warned the country that a period of painful change lies ahead - higher unemployment, changes to the tax system, and corporate restructuring.

One of the reasons that the LDP has slumped so drastically in the polls is because the government didn't believe the people would stand for it.

Now they have given Mr Koizumi such a strong endorsement, it will be fascinating to see not only whether he holds up to his promise - but also whether voters are genuinely willing to endure a period of pain in order to restore the world's second largest economy back to its previous strength.