David Cameron’s former chief of staff has predicted that the Tories will lose this May's general election because of a "collapse" in grassroots support, which has left them in a "pretty wretched" position.
Alex Deane, who worked for Cameron when he was shadow education secretary in 2005, said that the Tories would lose in the "ground game" to Labour, resulting in their leader Ed Miliband becoming prime minister.
The former Cameron staffer, who is now UK managing director of public affairs at FTI Consulting, told Public Affairs News: "The basic scenario in this Parliament has been clear for a while and remains unchanged in 2015: UKIP up, dividing the right, Lib Dems down, uniting the left.
"This becomes stronger as the election nears, because Labour’s ground game with unionists, volunteers and activists is far better than the Tory machine, which has been hollowed out at a local level – no amount of solid by-election campaign efforts can plaster over that collapse in the grassroots when facing the challenge of a general election.
"Research supports these intuitive points: I am that rare thing, a Tory who believes in polling, and seat by seat analysis is pretty wretched for the Conservatives. So, despite Miliband rather than because of him, my prediction for May is a Labour victory."
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This comes as Cameron has been dubbed a "chicken" and accused of trying to dodge the televised party leaders debates by insisting he will only take part if the Greens are included.
At the moment broadcasters plan to hold three debates. The prime minister, Ed Miliband, Nick Clegg and Ukip leader Nigel Farage have been invited to take part in at least one.
The Greens have been lobbying hard for Bennett be included in one of the debates. However the campaign suffered a serious blow today when Ofcom ruled it was not a "major party" in the same way that the Tories, Labour, the Lib Dems and Ukip are.
Asked this afternoon by ITV News whether he would decline to appear in the debates if the Green Party leader was excluded, Cameron replied: "Correct."
Miliband said the prime minister "should be able to stand on his record and stop running scared".
On Twitter, Farage said Cameron was "a chicken running scared over the TV debates". Ukip MP Douglas Carswell added: "If Cameron refuses to take part in TV debates, with what should broadcasters replace him? Tub of margarine? Bottle champers?"
However, chancellor George Osborne has come to the prime minister's defence, insisting that the debates had to "reflect the reality of the modern political landscape" and include all "minor parties".
He told BBC Breakfast: "David Cameron is the first person in our British political history who was seen as a likely winner of an election who then took part in election debates, previous people had refused to do that.
"He has taken part in election debates and we as the Conservative Party want to be part of election debates, but they have to be debates that are fair and reflect the reality of the modern political landscape."
Opposition politicians suspect Cameron wants Bennett included in at least one debate in order to split the centre-left vote in the same way Farage is seen to split the centre-right vote.
Osborne said: "If you are going to have the minor parties, you have got to have all the minor parties with a presence in Parliament who attract votes at elections.
"The Green Party did better than the Liberal Democrats at the last national election, for the European Parliament, and they have got one Member of Parliament.
"So we are just making a point that, if you are going to have all these parties, you have got to have them all. I think that would make a fairer debate and I think around 300,000 people have signed a debate saying that the Green Party should be involved, so it's not as if this is something that is just coming from the politicians. There is a group of the public who also want to see a big, fair debate."
Green party leader Natalie Bennett has reacted with fury to Ofcom's initial judgement. Writing for The Huffington Post UK she said: "Obviously, as leader of the Green Party, I'm deeply disappointed by this decision, but as a voter and citizen I'm also gravely concerned about the possible impact on British democracy if this stance is maintained in the final guidance.
"Ofcom is not only ignoring the views of the 275,000 people who signed the petition calling for the Greens to be included in the broadcasters' proposed leaders' debates, but also the evidence that 79% of the public want to see us in those debates (and 85% of women)."
She went on: "I do think we have people in positions of power who have very fixed ideas about what politics looks and sounds like, think that it's a basically an unchanging wrestle between the traditional big two, with a couple of satellites that squeeze into the gaps without really saying anything different.
"When you put together the support for the Green Parties of England and Wales, and Scotland, and Northern Ireland, with those for the Scottish National Party and Plaid Cymru, there's very strong backing for an anti-austerity alternative to the Coalition-Labour approach, as Nicola Sturgeon, Leanne Wood and I pointed out last month."