Increasingly vicious exchanges between the government and Labour over a proposed cap on housing benefit spread to the Commons today.
The government has not, as expected, laid an amendment to the opposition motion calling the government to revise its plans for housing benefit - prompting Labour accusations of confusion in the coalition line.
Iain Duncan Smith reacted angrily, accusing the opposition of "selling a complete pack of lies and nonsense" over the issue.
The row was lent an emotional aspect when a Labour shadow minister referred to the plans as a "sociological cleansing" of inner London.
The coalition insists the changes are necessary to relieve the burden of the ever-increasing costs of the benefit from the taxpayer.
A growing chorus of organisations have released data suggesting large numbers of urban poor could be forced further and further from city centres, especially the capital.