David Cameron's description of MPs who are opposed to launching airstrikes against Isis in Syria as "terrorist sympathisers" has incensed opposition MPs - even those who are in favour of military action.
Introducing today's ten-and-a-half hour Commons debate today, the prime minister was challenged repeatedly to apologise for the comment.
While he attempted to limit the damage by agreeing there was "honour" in voting against airstrikes, he refused to say sorry six times within the first half hour. "I respect that governments of all political colours have had to fight terrorism," he said. "I respect people who come to a different view from the government. I hope that provides some reassurance to members."
With just 30 minutes of the debate gone, Labour MPs Caroline Flint and John Woodcock, Lib Dem Tom Brake, SNP MPs Alex Salmond, John Nicholson and Ian Blackford all intervened on Cameron to ask he say sorry.
The self-inflicted wound should not prevent the Commons authorising Cameron's plan for military action, however it injected a level of bitterness into the day that the prime minister had up until now attempted to avoid.