Social media revolted at the comments, made by David Cameron to a group of Tory MPs, on the eve of an historic Commons vote that will decide whether Britain goes to war with Islamic State.
The Conservative leader, fearful of losing a vote on military intervention as he did in 2013, warned members of his 1922 committee against voting alongside a number of Labour MPs whom he alleged were sympathetic to the terrorists who recently wrought horror on Paris.
“You should not be walking through the lobbies with Jeremy Corbyn and a bunch of terrorist sympathisers,” Cameron said.
The comments sparked uproar on Twitter, with journalists, MPs and anti-war campaigners all quick to lambast the suggestion that their opposition to a fresh bombing campaign equated to sympathy for Isis.
Corbyn's unofficial campaign group led the charge, branding the remark "disgraceful".
Labour MPs, including Lisa Nandy, Wes Streeting, and Jonathan Reynolds followed suit.
Several reports also expressed their concern at "valid concerns" being rubbished.
While campaigners and anti-war lobbysits also expressed their disquiet with Cameron.
The vote, scheduled to take place after a hefty 10-hour debate on Wednesday, is expected to be close, but only called by the prime minister because he expects he can win it.
At least four Conservative MPs have said they will be joining the SNP, Greens and numerous Lib Dems in opposing the government's motion, which would extend air strikes currently being employed by RAF fighter jets in Iraq to Syria.