A few days before the 2010 general election, David Cameron was discussing the effects that spending cuts would have on government departments if the Tories came to power. The NHS budget, he said, would be protected, as would international aid. Elsewhere things would be tough and the cuts would bite hard. Cameron was, however, able to offer reassurances about the future of public services, including the police.

"What I can tell you is … if I win the election, if we win the election, [any cabinet minister] who comes to me and says, 'Here are my plans' and they involve frontline reductions, they'll be sent straight back to their department to go away and think again."

Just six weeks ago, the prime minister delivered a similar message in the House of Commons in answer to a question from the Labour MP Paul Farrelly, who complained that in his Staffordshire constituency of Newcastle-under-Lyme the police force was on a "cliff edge", with numbers falling to their lowest in a decade. Again, Cameron felt able to reassure him. "The fact is that the percentage of officers on the frontline has actually increased," he said.

Figures revealed by the Observer, obtained using freedom of information requests to all 43 police forces in England and Wales, suggest something altogether different.

In recent months it has been shown that the jobs of several thousand frontline officers – those who deal with the public rather than operate behind the scenes – have been lost as forces undertake the task of imposing the 20% of cost savings that have to be made by 2014-15.

But these latest figures are even more damaging to the Cameron defence. They have been independently verified by the House of Commons library and show that up to December last year, after 19 months of coalition government, 5,261 "first responder" posts – those who are not just "frontline" but are at the very sharp end, responding to 999 emergencies – had been lost. In several forces the percentage of losses has been well above 10%, and in Devon and Cornwall it is 25% of the total. The data is not yet complete and the total is certain to be higher now than at the end of last year.

The figures will have several effects. Certainly they will catapult the issue of crime and policing back to the top of the political agenda. Ministers can no longer say black is white and escape the reality through obfuscation.

Their problem is not just that there is strong data showing the frontline is suffering. It is also that after years in which crime declined – during Labour's period in power it fell substantially – there are now signs that it is starting to rise again. In January, figures from the British Crime Survey showed that personal crime, including theft, robbery and violence, had gone up by 11% over the last year – the steepest increase for more than a decade. The chief constable of Gloucestershire has warned of a "perfect storm" for his force as police numbers are cut, economic austerity bites, and the government imposes sweeping reforms, including the transition to elected police commissioners in November.

David Green, the director of the Civitas thinktank, said a link between falling police numbers and rising crime could reasonably be made. "Not all crime is equally susceptible to variations in police presence or activity, but crime that occurs in public places, including theft from the person and all violence, varies a good deal with the visibility of the police. Drunken fights, for example, might go no further than an unseemly scuffle if the police are near at hand, but may turn into stabbings or serious beatings without police intervention.

"The last Labour government was committed to neighbourhood policing and was beginning to make a reality of it. The coalition remains formally committed, but without the officers to carry out foot patrols its declared aims cannot be fully realised."

A perfect storm does indeed seem to be brewing for the government. Hard economic times are likely to increase certain types of personal, acquisitive crime. Richard Muir, from the IPPR thinktank, said the view among experts was that the period of falling crime might well be over: "Despite the government's claim that crime is simply fluctuating, it looks increasingly likely that we are at the start of an upward trend. This is to be expected given the rise in youth unemployment, although it has taken time to feed through into a higher crime rate. There is always something of a lag between the start of an economic downturn and a rise in crime, but the rise in personal acquisitive crime shows that this is now feeding through."

The result could be that the Conservatives' reputation as the party of law and order may be under threat, as could the party's relationship with the police service. Muir said: "The government is in a vulnerable position on crime in part because of its deteriorating relationship with the police service.

"It has alienated the Police Federation through a combination of job cuts, a pay freeze and pension reform, while it has alienated the chief constables by introducing elected police and crime commissioners. So, as crime rises, we may find the police putting the blame at the government's door."

It may also be that the Tories' (and Liberal Democrats') problem could well work to Labour's advantage. Cameron's pledge to protect frontline policing is now hard to sustain. As with his pledge to avoid any "top-down" reorganisation of the NHS, and not to meddle with child benefit, a promise appears to have been broken.

For Labour, the opportunity is growing to portray the coalition government as one whose leaders say one thing and do another. The issue of trust is becoming a difficult one for Cameron. Ed Miliband and his shadow home secretary, Yvette Cooper, may find that crime and policing becomes as fruitful an area in the coming months and years as the NHS already is.

The parallels are there. As with the NHS, Labour can accuse the government of meddling with a public service that most people believed was working and that was showing good results. It can accuse the coalition of trying to impose reform at the same time as inflicting massive spending cuts – an impossible mix.

Labour agrees that police spending needs to be cut, but by 12% rather than 20%, allowing the frontline to be protected. In short, it believes that police and crime could become the "new NHS", politically and in terms of public opinion. It intends to campaign hard on the issue ahead of the May local authority and London mayoral elections. With the Olympics approaching, the dangers for the government are obvious.

Cooper noted many parallels with the NHS as an issue, although she said concern over policing and crime would take longer to build as the evidence stacked up over time. "People rely on the police just as they rely on the NHS. They want to know that the police will be there at a time of need, just as they want to know the NHS will be there at a time of need."

Arguments over the health and social care bill have already done much to revive Labour's morale and may explain some recent improvements in the party's position in the polls relative to the Tories. Will crime and policing – traditionally a strong suit for the Tories – become another issue that damages Cameron and his party and has the reverse effect on Labour?