If the Tories lose this then the answer Michael Portillo should have given in 1997 when asked "Are we seeing the death of the Conservative Party as a viable force in British politics?", was "Yes!"
I don't see how they can do any better than Cameron: Anybody else, whilst probably attractive to the likes of Bono, simply won't sit as well with the electorate (unless Ken Clarke proves that 4th time is indeed a charm).
Clarke is even worse. At least Cameron isn't an europhile.
David Davis was awsome, but I guess the United Kingdom is too ungulfed in New Labour madness to even consider anything else. However, Cameron is going to produce the exact same result the "Conservatives" are going to face September in Sweden: when confronted with a copy and the original, the voters prefer the original.