David Cameron is set to be quizzed over the newspaper phone-hacking row that is threatening to engulf his communications chief.
The Prime Minister is expected to be tackled on the explosive issue when he faces questions in the Commons for the first time since Parliament returned from its summer break.
The pressure on key Number 10 aide Andy Coulson mounted again on Tuesday when the Home Affairs Select Committee launched a fresh inquiry into allegations that News of the World reporters hacked into public figures' phones while he was editor.
Committee chairman Keith Vaz announced the move after senior Scotland Yard officer John Yates indicated he was likely to speak to Mr Coulson as he considers whether to reopen the police probe.
And former NotW reporter Ross Hall told Wednesday's Guardian he is willing to testify. Mr Hall was named in a previous inquiry as the man who transcribed hacked voicemail messages.
Mr Coulson always denied any knowledge of the illegal eavesdropping, for which the NotW's ex-royal editor Clive Goodman and a private detective were jailed in 2007.
But one of his former reporters, Sean Hoare, reignited the row last week by publicly claiming his boss had been aware of the activities.
Downing Street insisted Mr Coulson's position is not under threat, and Mr Cameron - just back from paternity leave - is expected to mount a staunch defence of his aide at PMQs.
However, Labour MPs are set to try to capitalise on the furore by questioning the Tory leader's judgment in recruiting Mr Coulson as his top media operative.