Hilary Benn, the shadow foreign secretary, was the main focus of anger for protesters as he was accused online of warmongering and bringing shame on his late father, Tony Benn, who had strong roots in the anti-war movement.
Stella Creasy, MP for Walthamstow, north-east London, where campaigners had marched outside her office, was also targeted with hundreds of negative and sometimes abusive messages. She has promised to hold a public meeting on Sunday to explain her decision.
Jeremy Corbyn, the Labour leader, released a statement saying he would not tolerate abuse against MPs from any side. The bullying of Labour MPs “flies in the face of everything” he believed in, he said, and there was no place in the party for those who engaged in abusive behaviour.
Corbyn and John McDonnell, the shadow chancellor, have said there is no room for deselection of MPs and emphasised the inclusive, broad nature of the shadow cabinet.
The Labour leader and Tom Watson, his deputy who has called for new social media guidelines, will also email members before the end of the week, making clear that the party will not tolerate bullying or harassment.
However, some within the Labour anti-war camp believe deselection is a legitimate response to the decision of some MP to vote for the airstrikes on Isis in Syria.
Livingstone, a backer of Corbyn and co-chair of the party’s defence review, told LBC radio that the new, kinder politics was all very well but people had the right to try to get an MP they agreed with. “If I had an MP who had voted to bomb Syria then I would be prepared to support someone who was challenging them, as long as they were good on the other issues,” he said.
A Labour spokesman said Livingstone’s views do not represent those of the party.
Throughout the debate, MPs have been lobbied by Stop the War – which Corbyn chaired until recently – and Momentum, the movement of Corbyn supporters set up after the leadership campaign, to vote against the bombing.
Following the vote, the Stop the War Coalition condemned the “whining complaints from those MPs who apparently do not like being lobbied”.
“If an MP is not robust enough to withstand emails and tweets, they should really not be voting for bombing other people – those who wish to be alone with their consciences would do better to consider a life of religious contemplation. Stop the War will continue to hold to democratic account all those MPs who vote for war,” the group’s chairman, Andrew Murray, and convener, Lindsey German, said.
Deselection was openly being discussed by visitors to the Facebook pages of grassroots Momentum groups – including for areas that cover pro-airstrike MPs Harriet Harman and Neil Coyle in Southwark, Chuka Umunna in Lambeth, and Heidi Alexander and Jim Dowd in Lewisham.
However, a spokesman for Momentum stressed that the movement is “not a threat to MPs who voted for bombing” and that local groups would be barred from campaigning for deselection.
In a statement, the groups said: “We have made clear that we will not campaign for the deselection of any MP and will not permit any local Momentum groups to do so. The selection of candidates is entirely a matter for local party members and rightly so.”
The spokesman also said Momentum “strongly disapproves of anyone who engages in abusive behaviour towards MPs or anyone else, and threatening or bullying, whether they are outside the Labour party [as most are] or inside it”.
“We specifically asked our supporters to emulate Jeremy Corbyn, and to keep their messages about the issues and to refrain from any personal attacks,” he added.
However, some MPs called on the leadership to do more to deal with a vocal minority encouraging the 66 to be targeted, especially if they are in any way connected to the Labour party.
Two Labour MPs told the BBC’s Today programme that Corbyn was effectively permitting the bullying by failing to clamp down on some activists associated with threats towards MPs.
Wes Streeting, the Ilford North MP, who voted against military intervention, told the BBC: “Given how much this is being facilitated by Momentum and the organisation set up in the wake of Jeremy’s leadership campaign, I don’t believe that Jeremy Corbyn as an individual somehow encourages the bullying of Labour MPs, but I think at the moment he’s in danger of permitting it by not showing strong enough leadership and clamping down on this.
“It’s completely inconceivable for anyone to argue that there hasn’t been a well-organised, systematic and well-resourced attempt to bully MPs into voting against airstrikes on Syria.”
Ann Coffey, MP for Stockport, who voted in favour of airstrikes, said she received messages calling her a “warmonger” and a “red Tory” and warning that she would have “blood on her hands”, which she believes is from an email account previously associated with Momentum.
“If you have that at the top of the party, what you have is permission to target MPs, permission has been given to target us,” she said.
But senior Labour sources rejected the suggestion that there was more that Corbyn could do to deal with troublemakers. “Jeremy has repeated that there is no place in the party for abuse almost every single day,” the source said.
“There is a procedure to deal with such behaviour by Labour members and that is through the NEC. If there are threats from people outside the party then the procedure is not to moan to the media, it is to go to the NEC.”
This article was written by Rowena Mason Political correspondent, for theguardian.com on Thursday 3rd December 2015 11.54 Europe/Londonguardian.co.uk © Guardian News and Media Limited 2010