Tony Blair faces the threat of a Commons investigation into claims the police were dragged into politics ahead of a vote on terror detention plans.
Police say terror cases need longer investigation times
The Tories want an inquiry into the way chief police officers were asked to lobby MPs for a new 90 day limit.
MPs on the Commons home affairs committee may now examine the issue.
Home Office Minister Hazel Blears said it was "entirely appropriate" for police to make the case for detaining terror suspects for up to 90 days.
The plan was rejected by MPs on Wednesday in Tony Blair's first defeat as prime minister.
Conservatives Stephen Dorrell and Peter Lilley have tabled a parliamentary motion condemning ministers for "embroiling them in politics".
"The government asked chief police constables to lobby their local MPs in a way that I think runs the risk of politicising the police," said Mr Dorrell.
Mr Lilley said: "Every chief constable knows their job is up for re-selection in the next year or so. That puts great pressure on them."
The motion has been signed by 11 other Conservative MPs, two DUP MPs, Angus McNeil of the SNP and Lib Dem John Hemming.
Ms Blears denied the police had been playing politics by lobbying for 90 day detention, saying they had only being providing their expert advice.
She told BBC2's Newsnight. "It is entirely proper that the police were there to make their case and for Parliament to considered it.
"Certainly, as a Member of Parliament I would want to have the benefit of the best professional advice I could get before reaching my decision."
The home affairs select committee is also to investigate the role of chief police officers in the 90 day row.
Committee chairman John Denham said he did not think the police were necessarily being 'politicised'.
"It is worth remembering this was not originally a government policy," the Labour MP told BBC Radio 4's The World Tonight.
"It was a policy from the association of chief police officers. I don't think it is a surprise that they organised to try and get their policies through.
"It is very common for police officers to lobby members of parliament, including opposing government policy."
Mr Denham said his committee would be looking into the police's case for extending detention - but MPs would be free to raise the issue of alleged politicization.
Conservative committee member Richard Benyon said he thought the MPs should tackle the issue but still had to set the terms for their inquiry.
"If the home affairs select committee is not the right vehicle then we need to find other means of finding out who instigated this co-ordinated campaign," he said.
"Was that a suggestion from any special adviser or from 10 Downing Street? There is enormous anger about this."
Shadow home secretary David Davis also voiced his concern, telling Newsnight: "I think the position of the chief constables looks a little political."
Ahead of Wednesday's vote extending the detention time limit from 14 to 90 day, Andy Hayman, head of counter-terrorism at the Metropolitan Police, wrote a memorandum arguing the case for the plan.
He also joined Home Secretary Charles Clarke to meet Labour backbenchers and was interviewed on television and radio.
Conservatives say MPs also received telephone calls, emails and letters from chief constables.
Sussex chief constable Ken Jones, who speaks for the Association of Chief Police Officers (Acpo) on counter-terrorism, wrote to police chiefs around the country last Friday.
He asked them to make sure all of their MPs were informed about the argument for 90-day detention.
An Acpo spokeswomen said: "Of course we were contacting MPs. They needed to be informed before they made a decision.
"One of the purposes of Acpo is to give a professional view when we are asked for one."