David Cameron takes no prisoners as the EU referendum hots up
EU nationals, who may have lived in Britain for a few days or a few decades, are unable to vote in the 23 June referendum.
Now it has emerged they could even lose their right to live here if the UK opts for Brexit.
The Prime Minister is allowing an implied warning, that EU nationals already in the UK could face deportation after Brexit, to germinate. But is it the ultimate Project Fear argument?
Some say the Vienna convention on global diplomatic relations would automatically kick in to protect EU-born nationals living in the UK if the existing freedom of movement laws no longer applied.
But Downing Street is steadfastly refusing to concede that, when push comes to shove, those already residing in Britain will be allowed to stay here whatever the outcome.
Given another chance to do so this morning, a spokesman would only say: "It's possible there would be changes to the rights of people who have moved under the existing free movement rules."
The genesis of this bizarre row was an answer to a Parliamentary Question tabled by crossbench peer Viscount Waverly and exclusively reported by PoliticsHome.
Eurosceptic MPs have lined up to lambast the notion. Jacob Rees-Mogg said: "It would be straightforwardly immoral to deport people who have come here legally and who have established their lives here."
He surely has a point. Economic warnings are one thing, but allowing the threat of breaking families apart to linger and grow is difficult to justify.
Get the inside track on what MPs and Peers are talking about. Sign up to The House's morning email for the latest insight and reaction from Parliamentarians, policy-makers and organisations.