The trepidation is audible in the voice of the senior aide to David Cameron: “We’re pretty sure that Brown’s going to do something big next week.”

A rumour sweeping the Conservatives’ headquarters has the Prime Minister calling a snap election within days. On the last day of a feverish summer, a poll suggested that Mr Brown was growing in popularity and could be on course to increase Labour’s majority to 100.

Little wonder that Mr Cameron has broken out some traditional Tory tools to claw his way back into the game. Since returning from a brief holiday in France he has made a series of interventions on issues he had previously avoided. The murders of Garry Newlove and Rhys Jones prompted three speeches on crime in eight days. Then, on Wednesday, he used a television interview to speak for the first time on immigration. He has also raised expectations that the Conservatives will enter the next election with a commitment to cut inheritance tax, and is promoting the issue of Europe.

The blitz was conceived by Steve Hilton, Mr Cameron’s strategy guru, after the leader’s ill-fated trip to Rwanda. That visit infuriated the Right and became symbolic of the charge that he was failing to address issues of concern to ordinary voters. It is denied that the blitz is intended as a sop to activists. Aides claim that it is intended to scare Mr Brown away from an autumn election or, if that fails, to generate momentum before the poll.

Mr Hilton, who served with Mr Cameron on John Major’s 1992 campaign, became convinced of the need to dent the so-called “Brown bounce” before the start of the political season.

“We couldn’t have a situation with Brown going into party conferences with a ten-point lead,” one of Mr Cameron’s inner circle told The Times.

Mr Cameron’s team say that they have proved a talent for engineering momentum when it counts, citing the launch of his leadership two years ago which vaulted him from back-marker to front-runner in a fortnight. The May elections this year are said to be another example.

They insist that the burst of activity is not an echo of William Hague’s “core vote” strategy but a discreet campaign that balances its emphasis on crime and immigration with an attack on Mr Brown’s handling of the health service. It is not just the subject matter that raised eyebrows, however, but also the manner of its execution.

At a Westminster coffee shop last week, Mr Hilton’s shaven head could be seen bent over a draft document spelling out a mix of new and existing crime policies he had been working on with the speechwriter Danny Kruger.

With him was Andy Coulson, Mr Cameron’s director of communications. The former Editor of the News of the World and the former advertising executive were discussing what to call the document to be launched later that week. In the end it was called It’s time to fight back, a title in which Westminster observers detected more the hand of Mr Coulson than that of Mr Hilton. It followed Mr Cameron’s use of “Anarchy in the UK” after the Newlove murder, a phrase firmly in the tabloid lexicon.

Mr Coulson has made his presence felt in other ways. He has been courting a select band of senior journalists. He was seen dining with the BBC’s political editor, Nick Robinson, last week.

One Conservative commentator, defending the Tory leader against the claim that he is tacking to the Right, has written that journalists chose to focus on Mr Cameron’s intervention on immigration when covering his Newsnight interview without guidance from the Tories. This does not square with the facts. A decision was taken to flag up his remark that immigration “has been too high” to distract attention from another story – that of Mr Hague’s outside earnings. Mr Cameron was noticeably discomforted by questions about his Shadow Foreign Secretary. The ease with which two years of disciplined silence on such a controversial subject was sacrificed for a short-term media manipulation has infuriated close allies. One staffer said: “Steve wasn’t at all happy with that decision I think it’s fair to say.”

Friends of Mr Hilton say that he has a good relationship with Mr Coulson, whose appointment he helped to orchestrate. It is thought that Mr Coulson was among those who counselled Mr Cameron to cancel or at least curtail the Rwanda trip, while Mr Hilton opposed what he regarded as a capitulation to media critics. Senior Tories say that the pair will have to work hard to ensure that such inevitable tensions between strategic and tactical imperatives are resolved away from the public eye. Nor is theirs the only relationship in Conservative campaign headquarters that will be sorely tested in the months ahead.

The arrival of Lord Ashcoft ruffled feathers, a hostile leak last week suggested. Mr Hague’s former party treasurer has moved his “target seat” operation in-house in a deal with Mr Cameron that enhances his formal role.

Allegations that the peer is promoting the claims of Mr Hague and opposing “Team Cameron” appear to be unfounded. However, a senior Cameron ally hints at tensions between Lord Ashcroft’s belief in the benefits of targeted local campaigns in marginal seats and the “message framing” that is Mr Hilton’s speciality.

Another campaign veteran is more blunt: “Ashcoft and Hilton don’t get along at all.” In addition, there are questions over the extent to which the party chairman, Caroline Spellman, is really in control since Mr Osborne, as election co-ordinator, will take overall charge of the party machine as soon as a poll is called and has moved a team of his own staffers into the building.

Mr Cameron himself is reported to have established a permanent office in the headquarters for the first time and moved a number of staff from his Commons office into what will be the Tories’ election nerve-centre.

Tara Hamilton-Miller, a former Tory party press officer, quotes in the New Statesmana Cameron aide as saying: “Tactically our objective has to be knock Brown off his perch so far that he will shy away from an October election. He hasn’t got the guts.”

As we report today the Tories will step up their attempts to scare Labour with a poster campaign next week. The campaign is designed to neutralise what they expect to be a main thrust of Labour’s attack – that the Tory leader is former PR executive who doesn’t believe in anything. Meanwhile, Mr Brown maintains his silence. “He must be rubbing his hands in glee,” said a Shadow Cabinet member. Mr Cameron began his leadership promising a modern, compassionate Conservatism. He will say the latest phase is simply an emphasis on the last of those facets that did not, until now, generate media interest.

Thoughtful allies fear that by courting the Right he will become a prisoner of it. If the polls narrow, he will come under pressure to maintain focus on issues of traditional Conservative strengths. They are particularly annoyed about the use of immigration – a subject that Mr Cameron believed his predecessor Michael Howard mishandled. Even the focus on crime opened him to the charge of scaremongering. Ken Jones, president of the Association of Chief Police Officers, said: “People are distorting the figures for their own ends.”

The obvious risk is that this time Mr Hilton might fail to generate the momentum Mr Cameron needs. Then the option of a snap poll becomes yet more irresistible for Labour. As a member of Mr Cameron’s inner circle said with commendable understatement: “There’s quite a lot riding on this.”

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