Police officers have gathered outside Andrew Mitchell's constituency office wearing T-shirts with the slogan "PC Pleb and Proud".
Accusing the Prime Minister of failing to "get to the bottom" of the chief whip's angry outburst, officers from West Midlands, West Mercia and Warwickshire have congregated at the bottom of Sutton Coldfield high street in Birmingham.
The federations brought forward the launch of their campaign against police funding cuts after Mr Mitchell was accused of calling Downing Street police officers "plebs" in a foul-mouthed rant last week.
The launch had been scheduled to take place on Friday in central Birmingham, the city which will host the Conservative Party conference from October 7.
Ian Edwards, chairman of West Midlands Police Federation, said: "We feel the Prime Minister has failed to get to the bottom of this matter.
"It cannot be right that Mr Mitchell can deny making the comments attributed to him, contrary to the police officer's notes, and yet not come out and say what he did say.
"If he did call police officers plebs, and we have no reason to doubt the integrity of the officers involved, it's just another sign of the disrespect the Conservatives, the once heralded party of law and order, show to the police service."
File photo dated 05/10/2010 of Chief Whip Andrew Mitchell, who today denied calling a police officer a &quot;pleb&quot; during an altercation in Downing Street.