By Frank Luntz, the author of two bestselling books on political and business communication (THE TIMES, 04/04/10):

How is it that the Conservatives hold an eight-point lead over the most unpopular government in more than a decade? As the old joke goes, it helps to start with a 10-point lead.

Watching the election from the other side of the Atlantic, I’m amazed at how closely the Tories and Labour mirror the situation between the Republicans and Democrats in 2008 — and how Cameron’s Conservatives look more and more like John McCain’s fumbling Republicans rather than Barack Obama’s focused Democrats.

At this point you’re probably saying, “Who the hell does this Yank think he is?” First, I have observed up close every British election since 1987; I’ve met seven of your prime ministers and shared a drink with four of them. I’ve also conducted a number of “instant response” focus groups of the British electorate across the country that you can pull up if you go to the BBC website.

Second, it was a different David Cameron who captured the imagination of voters across the spectrum in my Newsnight focus group a little more than four years ago in a broadcast that many think helped propel him to leader at a time when he was trailing not one but two opponents. It was that Cameron — fresh, unscripted, forward-looking — who connected to the British electorate. It is that Cameron who is Awol today.

If asked to write about how Gordon Brown can achieve a hung parliament (I do not believe that he can win outright no matter what happens in the next five weeks) or how Nick Clegg can surpass his party’s 62 seats in the last election, I would do it. But since your deputy editor asked me to weigh in on the Cameron Conundrum, here goes.

1) “Change” is good, but “believe in better” is better. Yes, it’s the slogan from Sky’s ad campaign, but “better” is simply better than “change”. People would like something different, but what they really want is improvement. Obama realised early in his campaign that change was not enough. Without the “hope” component to his message, Hillary Clinton would have been the Democratic nominee. If Cameron doesn’t start asking voters to “demand better”, he will lose some of that precious change vote to the Liberal Democrats — and his outright majority as a result.

2) “Are you better off today than you were three years ago? Is your job more or less secure? Are your pension and your savings more or less safe? Are your taxes higher or lower?” There’s power in rhetorical questions, particularly those where more than half the population answer in your favour. Right now the Conservatives’ campaign strategy is to ridicule Brown in their “vote for me” campaign. Frankly, it’s silly. If they understood human psychology, they’d switch to a rhetorical approach. “Had enough?” has a far stronger appeal.

3) “Does this man \ really deserve 18 years?” That would be my poster campaign. Plain. Simple. Devastating. He wants another five years, according to the Conservative campaign. But this ignores the fact that he’s been chancellor and PM for 13 years. When you emphasise it would be . . . 18 . . . long . . . years . . . of Brown, even Alistair Darling’s wife would vote no.

4) “Make ’em pay.” The British are fed up with the pay-to-play lobbying scandal, the pay-for-peerage scandal, the expenses scandal and the implication that MPs are enriching themselves off the backs of the people. This is a perfect anti-Labour rallying cry for voters who don’t like the Conservatives but want to send a clear message to Westminster by voting out their incumbent MP. Invite voters to “punish their MP for punishing them”. A few egregious Tory MPs may lose their seats, but you’ll pick up dozens of Labour seats in return.

5) “Let’s cut the waste and let’s start with Westminster.” Call for an immediate 20% cut in Westminster spending: large enough to be credible but not so large that it will be hard to run the government. Make it personal: “Hard-working taxpayers have had to tighten their belts. It’s time for Westminster to tighten theirs.” It may be unpopular among backbenchers but it will draw a sharp contrast with the government’s “addiction to spending”. Voters will love it.

6) “I will root out waste, fraud and abuse.” George Osborne has repeatedly found himself on the defensive over the Tories’ deficit cutting policy. Holding Labour accountable for the misspending and mismanagement would put him on much stronger turf. In their debate I would have had Osborne ask Darling: “Could you name three areas where your government has wasted taxpayers’ money? What about two? Still nothing? How about just one?” In Darling’s (likely) refusal to answer (or even in his acknowledgment if he decided to be candid), you own the twin issues of “accountability” and “spending”.

7) “I will never raise taxes in a recession. Never. Never. Never.” It’s a strong soundbite but it’s actually much more. It appeals to the Tory base who feel Cameron has moved too far to the centre. It appeals to centrist voters who cannot afford to pay more tax. Better to draw a line in the sand than to be for tax hikes in one place and tax cuts in another. Conservative governments that raise taxes aren’t in government for long.

“My commitment to Britain.” Labour is flashing pledge cards. Conservatives should one-up it with commitment cards (a commitment is much more popular than a pledge) that include “measurable results” — specifics that Labour conveniently left off its cards. This comes eighth on the list but it may well be the most important. The Conservatives have to prove to Britain that they deserve to govern. Full stop.

The political cemetery is littered with the graves of challenger campaigns that demonstrated why the incumbent deserved to lose but failed to prove why they should win. John Major beat Neil Kinnock, George W Bush beat John Kerry, and Gerhard Schröder beat Edmund Stoiber despite all having horrible approval ratings, because their opponents utterly failed to make their case. If the Tories fail here, the Liberal Democrats will get more than 65 seats.

9) “I will work with anyone who will work with me.” What made Cameron so appealing in those early days was his positive tone and his public civility — even towards those he disagreed with. Someone needs to remind him it is possible to disagree without being disagreeable. It is electorally essential to invite people to embrace the future even if they haven’t embraced the Conservatives for 20 years now — and that requires a more positive approach.

10) “Gordon Brown thinks you work for him . . . and thanks to his tax hikes, you do. Let me be clear. You don’t work for me. I work for you.” Voters don’t judge a candidate based on a 90-minute debate or a 30-minute stump speech. On the contrary, a single witty retort or candid quip, played over and over again by the media, can overcome a mediocre performance. Cameron will undoubtedly have half a dozen lines, as will his opponents. The most effective will draw a direct comparison between Brown’s apparent aloofness and Cameron’s people-person approach.

11) Finally, David, dump the casual clothing and start dressing like a prime minister. You are not Obama. You may have hired Anita Dunn, his White House communications director, but what didn’t work for Obama (his job approval dropped almost 20 points in just one year and perceptions of his leadership collapsed) will also not work in Britain. You don’t have to look like a stuffy politician, but you do have to look like a leader.