The Conservative-led coalition is undermining the police with an unprecedented "campaign of denigration", the leader of rank and file officers has told the Guardian.

Paul McKeever, chair of the Police Federation of England and Wales, launched a blistering attack on ministers ahead of its annual conference this week. Relations between the government and federation, which represents 140,000 officers in England and Wales, are at an all-time low following government cuts to police budgets and proposed cuts to police pay, he said.

McKeever claimed the government reforms and cuts to policing were driven by "ideology" and would endanger public safety. He said ministers were claiming to support the police while actually attacking them, and using their allies in the media to plant "twisted" stories portraying officers terms and conditions as gilt-edged.

McKeever said: "I'm sure there is a campaign of denigration going on, both directly and indirectly from the government and their chosen thinktanks and through the press.

"Nobody [in the police service] has experienced this before. The government seems to have a real antipathy to police officers."

As evidence he cited "adverse stories about police overtime and payments which they know are twisting the truth and painting an untrue picture of what happens in the police service".

With the home secretary, Theresa May, due to address the conference on Wednesday, McKeever said he and his members were furious at the coalition: "The government seems to think it's OK to denigrate and kick cops on every occasion and it has gone too far.

"There is a thin veneer of pretence that the government is supportive of the police, but their actions speak much more loudly than their words."

McKeever added: "Past Conservative governments have treated the police service pragmatically. This government treats the police service as an ideological adventure playground for intellectuals."

The police leader warned of cuts leading to rising crime: "The cutbacks will affect the most vulnerable in society and those least able to defend themselves."

The federation says the pain that its members are feeling is revealed in its own survey, released to chime with its conference week in Bournemouth.

The survey claims that the 20% budget cuts have led 98% of officers to claim that morale has fallen in the ranks; 86% believe the fight against crime will be damaged; and 78% of federation members say their workload has increased.

Nine out of 10 officers who responded to the survey said that they fear colleagues will quit because of being unable to make ends meet.

The federation says officers could be left £4,000 worse off, without taking account of the effects of high inflation while the public sector is subjected to a two-year pay freeze.

The government has cut its funding of policing by 20%, and a review of terms and conditions recommended reforms that while seeing some officers gaining, will see more losing out.

Ministers deny that falls in police numbers will lead to a rise in crime and say officers can be moved from back office roles to those fighting crime.

The Home Office said: "The government's priority is to deal with the budget deficit and as a service spending £14bn a year of public money, the police can and must make their fair share of savings. Changes to police pay and conditions have been made by an independent review and are being discussed in the Police Negotiating Board."

Part of the Conservative-led coalition's array of plans for the police have hit a stumbling block. The Police Federation and government are negotiating pay and conditions, but it is expected the talks will stall and ministers will impose the cuts by autumn, in order to be able to see some savings in time for the next financial year.

Police officers cannot strike but protests including rallies and marches are expected. However, some figures in the federation want to put the issue of the right to strike back on the table.

McKeever said the home secretary would receive a cordial welcome from delegates when she addresses the conference on Wednesday.

Last week government plans for elected police commissioners were defeated in the House of Lords, although ministers are still vowing to drive it through parliament.

May told the BBC on Sunday that Labour opportunism was to blame for the defeat: "The Labour party has supported an element of direct election in terms of the oversight of the police. It was sheer opportunism from Labour peers in the House of Lords that went against Labour party policy."