A prominent Tory MP says voters are being turned off by David Cameron's "nudge-nudge wink-wink" approach to policy-making.
Zac Goldsmith also said he could imagine Boris Johnson as a "future and very successful leader of the Conservative Party.”
The Richmond Park MP, once rumoured to be considering giving up his seat to allow Johnson to return to Parliament, said the mayor had a "magic dust" appeal to voters.
And he warned that Cameron's promise of an EU referendum was muted because some did not believe it would happen.
In an interview with the Evening Standard, Goldsmith, who is campaigning against a third runway at London Heathrow, said: "I don't think people on the streets are clear enough about what Cameron stands for - and that's a problem in politics.
"You need to have a clear sense of direction and that cannot involve a lot of U-turns or nudge-nudge, wink-wink, which is effectively what our airports policy is.
"Even critics respect leadership and decisiveness and I do think we are lacking in that up to a point."
Goldsmith said he suspected Chancellor George Osborne of putting the third runway back on the agenda to signal the Tories' willingness "to do unpopular things for the economy".
"It's pure politics. But I don't think it's clever politics," he said.
Cameron's promise of an EU referendum was only "a partial game-changer" for voters because "there's a 50-50 chance they don't believe the promise", he said.
He urged the PM to risk a row with Liberal Democrat coalition partners by legislating before the end of this Parliament for a referendum after the election - something Mr Cameron yesterday indicated he was considering.
"There's a movement in the Conservative Party for this," said Mr Goldsmith. "I think it should be pursued. Let people know where their MPs stand on this big issue."
Goldsmith also confirmed for the first time that he had discussed with Mr Johnson the possibility of him standing down from his seat in south-west London to allow the Mayor the opportunity to re-enter Parliament in a by-election.
But he said that the idea only came up because it had been mentioned in an internet blog, and insisted that the scenario "was not realistic - it was not a real conversation".