The Socialist Equality Party condemns the brutal murder of Jo Cox, Labour MP for Batley and Spen, West Yorkshire.

Cox was just 41 years old and was only elected to parliament last year. She leaves behind two children and her husband, Brendan. Before that she worked for a number of charities including Oxfam, Save the Children and the National Society for the Prevention of Cruelty to Children.

Her murder has shocked millions throughout the UK and internationally. She died at 1:48 p.m. Thursday, after she was stabbed and shot multiple times following a constituency meeting in Birstall, West Yorkshire. A 52-year-old man, named as Thomas (Tommy) Mair, has been arrested.

The official Remain and Leave campaigns for the June 23 referendum on continued UK membership of the European Union suspended activity, as leading politicians on both sides and from all parties expressed their regrets. This does not detract, however, from the fact that what is known so far about the murder points to the role of the reactionary political climate generated around the campaign.

Cox herself was a prominent campaigner for a Remain vote, and it cannot be excluded that this is why she was targeted for a premeditated attack. Newspapers reported that only 24 hours before her death, she had tweeted that her husband and children were taking part in the “battle of the Thames” on a “Stronger In” boat commanded by musician Bob Geldof. Geldof had clashed with UK Independence Party leader Nigel Farage, who was staging a nationalist anti-EU protest involving fishermen.

The murder suspect, Mair, is reported to be a quiet “loner” and to have a history of mental illness, who had spoken of receiving “psychotherapy and medication.”

The Daily Telegraph has reported that he was previously a subscriber to S. A. Patriot, a South African magazine published by the pro-apartheid White Rhino Club. “The club describes the magazine’s editorial stance as being against ‘multi-cultural societies’ and ‘expansionist Islam’,” the Telegraph writes. “A blog post attributed to the group, dated January 2006, described Mair as ‘one of the earliest subscribers and supporters of S. A. Patriot’.”

As has now been demonstrated on so many occasions, it is most often such disturbed individuals that are destabilised during times of acute economic, social and political crisis. Britain is passing through such a period in a referendum campaign that could shake the whole of Europe, is already provoking economic turmoil and is spurring growing nationalist tensions within the European Union.

With so much at stake, the bitter divisions within ruling circles over the best means of advancing the interests of British imperialism are being played out in the form of threats of national collapse, appeals to jingoism and patriotism and, above all, xenophobia. Migrants from the EU and refugees fleeing from the wars in which the UK has played full part are being blamed by both sides of the campaign for the collapse of essential services, housing shortages and the destruction of jobs and wages that are all the product of the austerity measures imposed by successive Labour and Conservative governments.

It appears that this febrile atmosphere played a part in tipping Mair over from passive racism into a murderous rage. Several eyewitnesses said that he shouted “Britain First” or “Put Britain first” before making his attack on Cox.

Clarke Rothwell, who runs a café near the murder scene, said, “He was shouting ‘put Britain first.’ He shouted it about two or three times. He said it before he shot her and after he shot her.

“He leant down. Someone was wrestling with him and he was wielding a knife and lunging at her. Three times she was shot. People were trying to help her.”

Another witness, Hichem Ben Abdallah, said Cox was stabbed with a large knife. The attacker then kicked Cox as she lay on the ground before pulling a gun and shooting her.

Graeme Howard, 38, told the Guardian that he too heard the man shout “Britain first” before the shooting and during the arrest: “I heard the shot and I ran outside and saw some ladies from the café running out with towels. There was loads of screaming and shouting and the police officers showed up. He was shouting ‘Britain first’ when he was doing it and being arrested.”

Flynn-Edwards said, “She walked out of the library with her PA and he was waiting for her. He stabbed her first and this guy tried to stop him and then he shot her.”

Cox died while being attended by paramedics.

Prior to the arrest of Mair, there was a further non-life threatening attack on a 77-year-old man nearby, also attributed to Mair.

There is speculation that the cry “Britain First” might indicate that Mair also supported the far-right split from the British National Party, which has advocated physical attacks on Muslims and supports the UK leaving the EU. Late last month, Britain First issued a warning to British Muslim politicians that they would take “direct action” against them, citing in particular London’s newly-elected Labour Mayor Sadiq Khan.

Last weekend, the Mail on Sunday ran an expose on the extensive participation of neo-fascist groups in the official Leave campaign, including the involvement of leading personnel in Leeds, near to where Cox was killed. The Hitler-quoting and swastika-tattooed individuals are among a number of neo-fascists active in the Brexit campaign.

The pro-Leave Mail described this participation as a “hijacking.” However, the demands to end the freedom of movement of EU citizens and to prevent Britain from being flooded with refugees, especially Muslims, are the stock in trade of the far-right. They are now voiced first and loudest by the UK Independence Party (UKIP), before being taken up by the Tories and Labour as representing the supposed “will of the people.”

The same day Cox died, UKIP leader Nigel Farage was rolling out the latest poster in his Leave campaign, depicting a long line of refugees, with the words, “Breaking Point. The EU has failed us all.” In response, the Cameron government suggested that it would revisit its demands to end free movement either through further negotiations or a unilateral declaration.

For its part, top Labour figures including deputy leader Tom Watson declared that Labour too would no longer support free movement and would demand stronger policing of borders.

Cox’s death should sound a warning to workers throughout Britain. To prevent further outrages, it is necessary to take a political stand against the tidal wave of nationalist filth in which the Remain and Leave campaigns are seeking to drown opposition to austerity and war, and to strike out on a path of independent political struggle for socialism.