The immigration debate is underway in earnest in the House of Commons.
MPs are currently debating a Government amendment introduced by the Home Secretary which proposes stripping a terrorist suspect of British citizenship - even if that action were to leave the individual stateless.
It raises interesting questions about how you deport someone who no longer has a passport.
Downing Street says the Prime Minister has "lots of sympathy" for what one rebel, Dominic Raab, is trying to achieve.
Mr Raab's amendment, which has the backing of more than 100 MPs, was given time by the Speaker this morning.
It proposes curbing the power of judges to halt the deportation of foreign criminals who claim a right to family life in Britain under the European Convention on Human Rights.
But Home Office sources say the Immigration Bill already deals with this matter - and Mr Raab's amendment may have the unintended result of dragging the UK before the European Court of Human Rights more often.
What is clear from the threat of rebellion (the other amendments will be discussed shortly) is that David Cameron is unable to control his party on this issue.
Rebels tell me that if the Government wins the day (which is likely) it will lose "more and more hearts and minds" in the Conservative Party.
In off-the-record conversations I have had this morning, loyal Tory backbenchers refer to their rebellious colleagues as "lunatics" and "prima donnas."
The Immigration Bill exposes the rift which cuts through the Conservative Party in Westminster.