Hundreds of police officers are holding an emergency meeting to discuss what action they can take in their pay row.
Police say they are getting a pay award lower than inflation
Home Secretary Jacqui Smith is facing mounting pressure over her decision not to backdate a 2.5% pay rise for police in England, Wales and Northern Ireland.
Some 78 MPs have signed a motion tabled by the home affairs select committee chair, Keith Vaz, urging a rethink.
Delegates at the meeting have called for the home secretary's resignation over the dispute.
An overwhelming majority of those present at the meeting approved a motion saying that they had no confidence or trust in the ability of the home secretary to deal with their pay and conditions.
Police cannot strike, but leaders are attending the Police Federation crisis summit to discuss their next move, and to seek legal advice over possible industrial action.
Ms Smith is determined that the current pay deal should fall within public sector inflation targets, but she did not believe most officers wanted the right to strike.
Prime Minister Gordon Brown told MPs in the House of Commons the government had to ensure that pay settlements were affordable and consistent with wider pay policy.
"I would like more than anybody to be able to say to the police that we could pay their wages and their salary rise in full.
"But I have to say to them that no policeman and no person would thank us if their pay rise was wiped out by inflation," he said.
He added that police pay had risen by 39% over the last 10 years and that Scotland had been able to backdate the pay rise to 1 September only by putting plans for 500 more officers on hold.
Home Office Minister Tony McNulty earlier told BBC One's Breakfast the pay bill for the public sector was a "very significant" amount of money, but despite this, the police had been treated as a "special case".
"We have made sure that the police are in relative terms considerably better paid than others in the public sector."
But Jan Berry, chairwoman of the Police Federation of England and Wales, said its members would stand firm in their battle to have their pay rise backdated to September, like their colleagues in Scotland.
She told the BBC that officers were "very angry" and "fed up of being treated in this way" and that some members wanted to "renegotiate the law and seek the right to strike".
The federation was also seeking the right to judicial review of the home secretary's decision, she said.
As Ms Berry arrived at the Police Federation meeting later, she said: "The police officers feel betrayed, their trust and confidence has been shattered.
"It is disgraceful behaviour by the home secretary, we don't understand it and her excuses just don't hold water."
The chairman of the Scottish Police Federation, Norrie Flowers, said the Scottish Executive had honoured its agreement to backdate the pay deal and that Ms Smith "should do the same".
The police's 2.5% pay deal was decided through the independent Police Arbitration Tribunal.
While officers in Scotland are having their 2.5% pay rise backdated to 1 September, as the tribunal recommended, those in other areas will receive it in full only from December. This, officers say, will amount in real terms - due to inflation - to an increase of 1.9%.
The consumer prices index puts inflation at 2.1%, while the retail prices index, on which many pay deals are based, has risen to 4.2%.
POLICE PAY ROW
Earnings lost if 2.5% rise not backdated to September 2007
PC (entry level)
PC (after training)
The pay increase will see all police constables paid a minimum of £21,500, with those with the longest service receiving £33,800.
A total of 78 MPs have now signed Labour MP Keith Vaz's Parliamentary motion urging the government to backdate the pay award to 1 September.
More have signed similar motions put forward by Labour MPs John McDonnell and Lindsay Hoyle.
Mr Vaz told the BBC it was important the government "gave the award in full" and that it amounted to a small amount of money "in the scheme of things".
Labour MP for Reading West, Martin Salter, is one of those who have signed the Parliamentary motion.
He said: "We're asking police officers to tackle an ever-growing terrorist threat.
"We've got problems with rising gun crime and increasing knife crime, and particularly violent situations they're having to face on a day-to-day basis. We really need to keep that bond of trust."
'No ordinary rights'
Officers from each of the 43 forces in England and Wales are attending Wednesday's Police Federation crisis summit in London.
PUBLIC SECTOR PAY
Police constables currently start on £21,009
Teachers' starting salary is £19,161 in England and Wales. In Scotland it is £23,316
New prison officers earn £18,483 in England and Wales. In Scotland they receive £14,373
Lower grade civil servants, such as administration assistants, begin on between £11,750 and £14,083 depending on department
Firefighters start on £20,396, rising to £27,185 after reaching "competent" status
Source: Unison 2006 figures, Fire Brigades Union
They will be joined by representatives from all the police staff associations, including the Police Superintendents' Association and the Association of Chief Police Officers.
They will be asked if they want to behave more like a trade union, or press for an independent pay review body whose decisions are binding on both sides.
An act of Parliament bans police officers from taking strike action because of the critical role they hold in society.
Ken Jones, president of the Association of Chief Police Officers, said: "I feel we are not giving sufficient weight to the fact that cops don't enjoy the ordinary rights of other workers in terms of industrial action."
The chairman of the Dorset Police Federation, Clive Chamberlain, added: "We've got to have some means by which we can register our disapproval and have the same type of employment protection that other employees have. We don't have that."