Bruce Anderson: David Cameron has shown courage and strength under fire. He deserves to win

The events of the past week could have undermined a lesser figure

Beyond distaste, he had two reasons for refusing to answer the question on drugs. A few years ago, asked whether they had ever smoked pot, a number of shadow ministers replied "yes". The tone of their answers ranged from sheepish to boastful. The whole affair made the Tory party look silly. Observing this, Tony Blair decreed that he and his ministers would refuse to answer similar questions. David Cameron is certain that the PM is right (I also suspect that Messrs Blair and Cameron's undergraduate careers were not wholly dissimilar).

David Cameron had a second reason for refusing to comment. Lots of youngsters dabble in drugs. Most of them come to no harm. But not all. There are casualties. It is hard enough already for parents and educators to persuade their charges of the unwisdom of drugs without the impression being given that experiments are a normal part of growing up.

In recent years, since a member of his own family developed a problem, Mr Cameron's views on drugs have grown steelier. These days, he is less interested in philosophical discussions about liberalisation than in more residential rehab units. David Cameron would hate to say anything which might inadvertently encourage some youngster to take drugs. That helps to explain his initial response. A number of his colleagues have been impressed by the way in which he has stuck to his course.

Now, the first ballot is tomorrow. David Davis is still almost certain to top the poll, but without the momentum which once seemed possible. Before the party conference, the Davisites had 66 declared supporters plus a few sleepers; and they wanted to ensure that their final figure was high enough to cause a surprise. Over the past few days, however some of the sleepers have gone to sleep. Equally, a few of those who declared because they had thought that they were backing an inevitable winner are now unsure. Their manner is less triumphant devotee, more reluctant conscript. Some may still desert.

There were two questions which the Davisites find it hard to answer. The first is whether they think that their man could become prime minister. The second: whether he ought to. There is also an instructive recent comparison between the two Davids when it comes to adversity.

David Cameron has an unexpectedly difficult week. He stays calm; his team stays supportive. David Davis has a difficult week. He does not stay calm. He starts blaming everyone else, beginning with Andrew Mitchell, one of his oldest friends. It does not cross his mind that he may be at fault.

Liam Fox is now trying to persuade some right-wingers that only he can stop David Cameron. Why any right-winger should wish to stop Mr Cameron is beyond me. The idea that he is some sort of leftie would come as news to anyone who remembers how much he enjoyed working for Michael Howard when Mr Howard was home secretary. Mr Howard's implacable refusal to accept the Home Office's defeatist platitudes on crime won his young adviser's admiration. David Cameron has often cited this as proof that a resolute minister can make a difference.

Any supposed right/left split between David Cameron and Liam Fox is merely a matter of emphasis and temperament. Mr Cameron is determined not to make any concessions to the simple-minded right. On Europe, tax, school vouchers and the public services in general, he knows what he wants. He also knows that it will require time and relentlessness. He believes in following Michael Howard's example, not Tony Blair's. Mr Blair arrived in Downing Street believing that it should be easy to reform the public services. Over the past eight years, he has undergone a learning process; the most expensive one in history. It has cost tens of billions of tax-payers' money to achieve a partial cure for Mr Blair's naivety. Mr Cameron has no intention of repeating those mistakes.

Liam Fox is able, charming and eloquent. But he is sometimes keener on clap-lines than on complexity. In some indefinable yet also self-evident way, he does not have as much political weight as David Cameron. This may not prevent him beating another heavyweight, Kenneth Clarke.

There are reports that Ken is seriously fed up. What more could he have done? He took the selection campaign seriously. He tried to remember the names of new MPs. He even acquired a mobile phone. Yet, despite all these gracious concessions, his colleagues seem determined not to vote for him in sufficient numbers. He cannot understand it.

Yet as with David Davis, it is his own fault. In order to have a serious chance of winning the Tory leadership, he had to emulate Henry IV of France, who became a Roman Catholic in order to ease his way to the French throne; "Paris is worth a mass." For Ken, Downing Street should have been worth a genuflection to Euro-scepticism. But he refused to decommission his views on Europe or put his Europhilia beyond use.

Instead, he tried to mislead his colleagues, claiming Europe would not matter for the next 10 years. As he well knows, this is nonsense. Europe always matters. Even if we are in no danger of losing our currency, or being forced into a federalist constitution, there is an unending stream of directives and other legislation. Many in Brussels are determined to slip the constitution through in dribs and drabs, hoping that no one will notice.

Lots of Conservatives do notice. They want a leader who will resist all this, not one who will tacitly encourage it. That is why Ken is in serious danger of being the first candidate to be eliminated.

It is unfair, just as it was unfair that poor Malcolm Rifkind could not get enough support to justify a run. But only a fool went into politics expecting fairness. Neither Ken Clarke nor Malcolm Rifkind are fools.

It must be galling to have held so many great offices and still be spurned. But that is the brutal evolution of the political process. Even so, Mr Clarke or Sir Malcolm would be an adornment to any front bench. They could help to enhance the Conservative Party's prospects of winning the next election. It is to be hoped that they agree to do this, even if it means making somebody else prime minister.

My choice for that somebody remains David Cameron. Mr Cameron has brains, judgement, charm, eloquence and courage. He may have a magic ability to communicate with the British people in a way that restores the excitement to Toryism and encourages the voters to forget all the travails of the past 15 years. The events of the past week could have undermined a lesser figure. There is no sign that they will prevent him from winning the leadership.