The Prime Minister is facing a growing backbench backlash over plans to expand the Government's powers to monitor the emails, texts and website visits of every person in the UK.
Internet companies will be instructed to install hardware enabling GCHQ - the Government's electronic "listening" agency - to examine "on demand" any phone call made, text message and email sent, and website accessed.
This information could all be accessed without a warrant.
A previous attempt to introduce a similar law was abandoned by the former Labour government in 2006 in the face of fierce opposition from the Conservatives and the Liberal Democrats as well as civil liberties groups.
Senior MPs from both coalition parties have lined up to condemn the move by ministers to revive the plan.
The Home Office argued that the measure was "vital" to combat terrorism and organised crime and stressed a warrant would be needed in order to access the content of the communications they were monitoring.
"It is not focusing on terrorists or on criminals. It is absolutely everybody," said Conservative former shadow home secretary David Davis.
Attempts by the last Labour government to take similar steps failed after huge opposition, including from the Conservatives.
A new law - which may be announced in the Queen's Speech in May - would not allow GCHQ to access the content of emails, calls or messages without a warrant.
But it would enable intelligence officers to identify who an individual or group is in contact with, how often and for how long. They would also be able to see which websites someone had visited.
Conservative backbencher and former shadow home secretary David Davis said it would make it easier for the government "to eavesdrop on vast numbers of people".
"What this is talking about doing is not focusing on terrorists or criminals, it's absolutely everybody's emails, phone calls, web access," he told the BBC.
"All that's got to be recorded for two years and the government will be able to get at it with no by your leave from anybody."
He said that until now anyone wishing to monitor communications had been required to gain permission from a magistrate.
"You shouldn't go beyond that in a decent civilised society but that's what's being proposed."