It looks as if one over-exposed potential candidate - Boris of course - and one already over-exposed Cabinet minister - Sajid Javid - are both jostling for the all-important Euro-sceptic vote. Javid's back story has already made him the darling of Conservative MPs and the right-wing commentariat, and he's been beefing it up with reminders that he's basically a good Thatcherite ever since he hit the headlines. His 'House' magazine interview also ensures we all know - as if we hadn't already figured it out - that yes, he's a euro-sceptic too. Boris is consistently all over the place, but he never intentionally misses a populist opportunity, and so has been telling 'Time' magazine that a British exit from Europe would be very manageable indeed - Guido gives the relevant quote here.
The pity about Javid is that he combines an interesting back story with pretty well the whole panoply of right-wing opinions that appeal so much to hard-core Tory members and the Conservative columnists, but so consistently fail to do much to elect Tory governments. Since John Major, over the course of four Tory leaders, the only one to have been elected - and then on a minority basis - has been David Cameron, also the only one not to have embraced rightist notions in his pre-election period. The other three, determined euro-sceptics and neo-Thatcherites all, got nowhere near (and one didn't make it to the election).
David Cameron remains far more popular than his party, but while his party is still pretty toxic with the voters, he is pretty toxic with Conservative MPs. You do sometimes wonder whether Tory MPs and their cheerleaders are existing in some Kafka-esque universe where they will only be happy if they elect the most right-wing of leaders, only to watch him (or her) fail, so that they can begin the "actually he wasn't right-wing enough" post-mortem. The Tory Party used to be focused on unity behind a leader, and pragmatic centrism towards the electorate. The defenestration of Margaret Thatcher saw the abandonment of both, and they've never won a majority since.