The SDLP and the Ulster Unionists are involved in a furious row over policing.
The Ulster Unionist policing spokesman, Fred Cobain, has accused an SDLP campaign advert of "naked sectarianism".
The SDLP ad reads "OUT", directed at the RUC, British symbols, special branch and the former chief constable Ronnie Flanagan.
"IN", it said, were the Ombudsman, the new PSNI chief constable, Hugh Orde, 2,000 more Catholic police officers and end to human rights abuses.
Mr Cobain said the SDLP's suggestion that human rights abuse had been widespread was outrageous and he was sorry that a party that portrayed itself as the moral guardians of the Agreement was stooping to Sinn Féin tactics.
The SDLP's policing spokesman, Alex Attwood, however, said the party's record was a proud one and had delivered change.