Theresa May might want a positive Tory party – but Lynton Crosby is running the show

Theresa May is a complex voice in the Conservative party. Her demand for a positive election campaign last night is in the same vein as her application of the 'nasty party' moniker in 2002. She is not a wet – far from it – but she clearly sees the need for the party to offer a more nuanced and upbeat message than it is currently capable of.

She told an event for prospective female Conservative candidates:

"I'm a great believer, as a candidate, in running a positive campaign. I think what people want to know is, what would you do for them? So where you've been a member of parliament you can refer to what you’ve already done and what you will do in the future."

May clearly wants the party to offer voters an aspirational vision of the world, one of the sort which worked so well for Margaret Thatcher among the upper working and lower middle classes. But that is very far away from where the Conservative party is today. Under the strategic leadership of Lynton Crosby the party has done what every party does under his tutelage: hammer away negatively on areas where it polls positively.

Toward the tail end of 2014 there were some promises of electoral sweeteners – admittedly uncosted and set for some time in the distant future – but in 2015 the Tory message has been universally negative.

This starts with the approach to Labour. Miliband is relentlessly mocked as weird, a tactic Michael Gove specifically took umbrage at recently. The party's warnings about Labour in office are borderline hysterical, veering from Trotskyism to 28 Days Later.

And its policy proposals are no more positive. Yesterday David Cameron said unemployed young people would be forced to do six months unpaid community work to get their benefits. It didn't matter that London's post-riots 'Day One Support for Young People Trailblazer' scheme had shown these initiatives to be counterproductive and ineffective. Under Crosby's leadership, these measures poll well, so they are pursued.

IDS is said to have urged caution on the obesity plans

It's telling to compare it to Labour's pledge of a compulsory jobs guarantee for the young unemployed. The policies are not actually that different, but the spin is worlds apart. What Labour presents as an offer, the Tories present as a punishment.

It is precisely the same message on obesity, with Cameron insisting the obese will lose sickness benefit if they do not diet. It's a nonsense policy, designed for headlines rather than implementation.

Again, the policy is not so different from the type of initiative once pursued by Iain Duncan Smith, who gave JobCentre Plus the authority to cut jobseeker allowance of those who refuse treatment for drug addiction. But it is interesting that IDS' message was once one of social justice. It started with the aspiration and followed up with the penalty. Now that chronology has been reversed. As a communication strategy, it is very revealing.

These policies may poll well, but they offer nothing to an aspirational voter. They do not promise to improve their lives, only to make the lives of others worse. That's the crucial distinction between strong polling and a winning election strategy: people may support restricting benefits, but to get them to the polling booth you need to give them something to improve their own lot.

Labour lags behind the Tories in all sorts of areas, not least of which are the tent-pole measurements of leadership and the economy. But its clear lead on living standards explains why it manages to maintain a slim poll lead despite relentless negative press coverage and an uncharismatic leader. Living standards are not just one measure among others. They are a signal to voters that you will try to make their lives better.

Miliband lags behind, but Labour maintains slim poll lead

Nowhere is the absence of a positive message clearer than on immigration. If ethnic minorities had voted for Cameron at the same rate as the white British population in 2010, the Tories would have won 500,000 more votes, 24 more seats from Labour, and a parliamentary majority.

In 2015, the ethnic minority vote will be even more influential, with another 500,000 taking part. In 70 seats, their share of the electorate in twice as large as the current majority of the incumbent.

But these voters will not back the Tories. Just 24% of Indians and 13% of Pakistanis support the party, despite typically sharing its social conservatism and suspicion of benefits. Labour's hold over these groups is slipping, but the Tories don't benefit.

And why would they? In power they championed 'go home' vans, immigration raids and Tube immigration checks. They did nothing to fix a Kafkaesque immigration system which often traps people in a bureaucratic nightmare for years. Pakistani voters are rarely able, for instance, to bring family members over to the UK for weddings. They are treated as second-class citizens in their own country.

Of course, the public are sceptical of immigration – as are many ethnic minority voters. But trapped between that sentiment and its inability to tackle EU migration, the Tories have allowed a militarisation of immigration enforcement to take place which has a deep emotional impact on ethnic minorities.

The Conservative pro-business message should appeal to London, but the city is resistant to the party's charms

London – a bastion of wealth which should be seduced by the party's pro-business message – is resistant to the Tories. It won 34% of the vote in the capital in 2010, but by last year's European election that had dropped to 22%. Labour currently has a ten-point lead.

That's partly a demographic phenomenon. Thirty-seven per cent of the capital is foreign born and the party's messaging has pushed them away. But it is also about attitude. London is based on positivity and dynamism. It is a place for people who want to accomplish things. They come from across the country and the world to do so.

They respond to political messages based around positivity and improving people's lot. The relentless negativity of the Tory campaign does not speak to them.

It's too late for the Tories to change in time for May. This election is based on a core vote strategy, for Labour and the Tories. For Miliband, that means focusing on policy areas he is already favoured on. For the Tories it involves appealing to older, more negative voters of the type more likely to drift to Ukip. At is heart, it is an appeal to resentment and suspicion.

It might just get the Tories over the line in 2015. But it is no way to remodel a party which has not won an election outright since 1992. A future May leadership would clearly try to offer voters something more upbeat than the Tories are currently willing to countenance. But after Cameron joined the list of political leaders who tried – and then gave up – it's far from clear that she'll be any more successful.