A simple plan: pick the person who plays best at the box office

The Conservative Party has always claimed "choice" as one of its fundamental tenets. Indeed, at the moment the party is so committed to this principle that it is offering five candidates for the leadership, with Kenneth Clarke yesterday, in his own good time, joining Michael Portillo, Iain Duncan Smith, David Davis and Michael Ancram in the race for the Hague "inheritance" (if that is not too dignified a term for it).

It was refreshing to see Mr Clarke's breezy, polished performance at the Institute of Directors. It reminds us of what we have been missing during the last few years of Mr Clarke's purdah. He is, as he showed yesterday, a major league player, and his decision to run for the leadership lends the contest some gravitas. But the real choice facing the Tories – which, to their credit, most of the candidates seem aware of – is between survival and extinction. The next election may not quite be the Tories' last chance, but they would do well to be wary of complacency.

Which brings us to the candidature of Michael Ancram. Ignore the fact that he is an aristocrat, although this is not the ideal starting point for a modern political leader. Far more relevant is his rejection of "stardust and spin", which tells us a good deal about his approach. It is Hagueism by other means, an approach that could be cruelly but accurately put down as "one more heave".

The only reason to support Mr Ancram is as a caretaker candidate, useful in some ways until a referendum on the euro is held (which might, of course, be an uncomfortably long time). The truth is that a building in such a state of disrepair and as divided against itself as the Tories' house needs something more radical – a builder, an architect even – than a caretaker.

And radicalism, or at least a whiff of it, is what Iain Duncan Smith and David Davis offer. It is not, however, the sort of radicalism that will take the party closer to the electorate. They are both fishing in the same rightist pool, which may do their cause no favours. Of the two, Mr Davis has the edge in energy and modernity and has shown more thoughtfulness about the future of the health service and the welfare state. He is fresh and untainted and could prove popular with his party. But one suspects he would have been better continuing to harry the Government as chairman of the Public Accounts Committee. In any case, the voters are unlikely to find a dish of reheated Thatcherism all that appetising, whether the chef is Mr Davis or Mr Duncan Smith .

Which leaves us with Mr Clarke and Mr Portillo. These are the two names that should be presented to the 300,000 party faithful, since they are the most likely to revive the party and challenge Tony Blair.

They both have flaws. Mr Clarke's insouciance about sending Vietnamese people to their death from tobacco-related illnesses speaks of a certain carelessness throughout his career (remember his remarks about ambulance staff being "glorified taxi drivers"?) Additionally, for all his charm, it is difficult to see how Mr Clarke would lead an overwhelmingly Eurosceptic party. Mr Portillo's newly discovered brand of compassionate conservatism could prove confusing to both his party and the wider public, while there are also valid questions over his judgement. More than any of his rivals, however, he recognises that the Tories must adapt to the modern world.

Both Mr Clarke and Mr Portillo are intelligent, seasoned and talented figures of the first rank. The choice, to borrow Peter Mandelson's phrase, is about who "plays best at the box office". This is what must be paramount in the Tories' minds as they make their choice this summer. The future of their party depends on it.