In an exclusive interview with PRWeek, Greenberg said: 'I'm not impressed with what Cameron has done. Cameron has got good marks, people like him. But there's little sense he has changed the Conservative Party itself and I think that leaves it vulnerable to what happens in the election.'
PRWeek has learned that Greenberg is lending a hand to several Labour MPs for the forthcoming general election (see News, page 2).
Greenberg has been regarded as one of America's pre-eminent pollsters and political strategists since he helped Bill Clinton first get elected in 1992. He has worked for Nelson Mandela, and helped Tony Blair to achieve Labour's landslide election victory in 1997.
Greenberg, now a consultant for Edelman, said Cameron had failed to go as far as Blair in standing up to his own party: 'Before Blair was elected, when you did focus groups, people wanted to like him, they liked him, they thought he was charismatic. But at the same time there was this sense of "Is he smarmy? Is he real? Is he authentic?"
'Real conflict was what people used to judge whether he was real. Reining in his own trade unions, saying that he wouldn't raises taxes, doing things that are not popular in his own party. Those are real things and they say to people that he's authentic.
'There's the same pattern with Cameron. People think he's charismatic and a very good speaker, but is he real? They're also conscious that he is from a PR background. Smartly, people look to behaviour. Is he willing to do things that cost him, particularly among his own supporters? I don't think people have seen that ... I don't see him battling for enduring changes in his own party.'
With the general election due to take place this June at the latest, Greenberg added that Cameron had now left it too late to pick the necessary fights with his own party:
'It's hard to do that now - you don't get into a fight with your own people three months from an election. It's too late for that. Labour did some things late, but we didn't fight with our unions during the campaign period.'
As Conservative strategists look to position Cameron as the 'change candidate' in the next election, Greenberg's comments could set alarm bells ringing at Conservative Party Campaign Headquarters (CCHQ). No-one at CCHQ was available for comment as PRWeek went to press.
In his career as a pollster and adviser, Greenberg has a wealth of experience working for candidates who promised change, helping to craft their campaigns and using sophisticated polling techniques to track how those ideas played out with the public.
Greenberg is CEO of polling firm Greenberg Quinlan Rosner, which he set up in 1980. Since 2009, he has also worked as a s senior consultant for Edelman, advising the agency and its clients on corporate strategy globally.
GREENBERG ON ... THE POLLS
'I'm not impressed with the support Cameron has won ... Our support for Labour prior to the 1997 election was in the 50s for a long period. It only dropped right before the election. Ultimately we got 46 per cent of the vote. '
'At his best Cameron is pushing 42 per cent support. He's hovering around 40 per cent. So if he was to lose support to 39 or 38 per cent, he would be in hung Parliament land.'
'It can get closer. In Britain the campaigns do impact on the majority. Cameron needed to have an enduring 45 per cent before the election got going. Forty is where he wants to end up ...'
THE ELECTION BATTLE LINES
'This a change election. Change versus more of the same. The Conservatives' playbook is straightforward given how long Labour has been in power; given the sense the country is on the wrong track. They'll run on "time for a change". They'll run a contrast between the future in Cameron, and Brown as the man with responsibility for the past.'
'What Labour is going to have to say is you can't trust (the Conservatives) to bring the change. They say that they're running on change, but what type of cuts are they going to make? Who is George Osborne? Do we trust these people to manage this very difficult economy? Basically Labour is going to say "yes we want change, but let's not put at risk our growth and public services". That is essentially the context for the way Labour would rephrase the debate.'
'Labour will make the argument you can only trust Labour to make the cuts. It will also argue that as the economy is beginning to come back, you don't dare put it at risk. But it's pretty early on in the recovery ...'