The Labour right has been engaged in a campaign to delegitimise the left for months. By "left" I mean anyone who isn't acceptable to the right, and by "months" I mean years. For all the recent increase in vituperation and outrage, including the tales of Twitter-terrorism and prophecies of a deselection blood-bath, this has been going on since Ed Miliband won the leadership election in 2010. John McTernan's metamorphosis into a walking bile-duct didn't happen overnight. You might even argue that the narcissism of small differences that marked the Blair-Brown feud so raised the base volume that when genuine policy disagreement returned to centre-stage it obliged the right to turn the dial up to 11.
The hysteria of the right's response is ironic, given their insistence that the left is expressive and self-indulgent, but it also points to the degree to which the right and centre of the party, from Miliband to Miliband, have been influenced by American politics since the late-80s. It's always worth narrowing your eyes when anyone tells you that politics has fundamentally changed, but I think there has unquestionably been an increase in "partisanship" in US politics since the conservative revanche of the late-70s, which long predates the distorting lens of Fox News. This is primarily observed as an increase in policy polarisation, as measured by votes cast in Congress. In other words, "two coherent ideological parties with very little programmatic overlap".
However, looked at from another angle, this is actually evidence of greater hegemony, not division. Issues that once cut across party boundaries, such as civil rights and the war in Vietnam, have waned, while the issue of the role of government in the economy, on which the parties are distinctly aligned, has waxed. But for all the hyperbole and legislative standoffs this has given rise to, the policy divide between the parties has narrowed as the neoliberal consensus has taken root. That Barack Obama's Affordable Care Act was based on a system introduced in New Hampshire by Mitt Romney is typical: more huddling around the poles, but the distance between them is shorter.
The chief paradox of the growth in partisanship is that it has been mirrored by the rise of the idea of politics as a rational consumption preference. This originated in public choice theory in the 1960s, though most commentators date its arrival on the political scene to the 1980s and the intersection of identity politics. According to John Gray, "Looking back, it becomes clear that Corbyn is one of the by-products of a project of marketisation, begun in Britain by Thatcher and continued during the era of New Labour, which has been pursued in different forms in many countries" (in paying £3 to vote Jezza you were cheaply satisfying your ego). The consequences of marketisation are profound: "The new politics may be more volatile; voters are less tribally loyal and more likely to shop around".
This has caused a compensatory heightening of political language in an attempt to instill brand loyalty: "partisan animosity is one of the few forms of discrimination that contemporary American society not only permits but actively encourages". In an era when politics is so heavily mediated, and policy differences often paper-thin, selling the product is frequently reduced to dog-whistles and stereotypes that provide the quick hit of a prejudice confirmed: "If you’re trying to get the largest return from voters, it would make sense for politicians to try to activate social identity rather than focus on policy". This both reflects and reinforces a wider division of society into mutually antagonistic camps that increasingly identify as social movements, with membership (preferably a lifetime subscription) implying acceptance of a basket of signature positions.
A characteristic of the partisan era is that the lack of substantive disagreement in the economic sphere leads to greater intransigence elsewhere. This takes two forms. First, emblematic issues touching on the role of the government in the economy, such as Obamacare, are over-dramatised ("death panels" etc). Second, social issues (marginal to the major economic conflicts) that might feasibly have led to pragmatic bi-partisan action, such as gun control and abortion, become emblematic standoffs. This creates a void in which opportunistic populists like Donald Trump can thrive, running a campaign based on bumper-stickers in which policy impossibilism is a virtue.
In the UK, party politics remains more class-conscious and ideologically varied (even after the neoliberal tide), hence the lesser significance of the culture wars despite the best efforts of the media to make "political correctness" central to our lives. Consequently, the partisan divide is as likely to be found within parties as between them (e.g. unilateral nuclear disarmament or the EU), originating in more fundamental tensions, such as isolationism and internationalism. This leads to regular talk of splits and the prospect of third-party breakthroughs. Roy Greenslade is the latest to claim that Labour is "on the brink of complete disintegration" because "the church is simply too broad and too battered to act any longer as a coherent united party".
This is a refrain that the Guardian has sung for half a century. The novelty is that the "incoherence" is now painted as the product of cultural dissonance rather than economic contradictions. Thus "poncified" London Labour is unable to connect with the bigoted Northern working class. The insistence that opposition to Syrian airstrikes is a matter of bullying and sexism is likewise an attempt to shift the debate from policy to culture. A similar tactic was adopted during the Scottish referendum against the "cybernats". It failed then both because of the incongruity of bruisers from the Labour right presenting themselves as champions of women and the bullied, and because the Scots actually wanted to talk about the substance of independence.
The current irony is that the Labour right is adopting a partisan style while trying to exterminate the social movement that is providing the party with (limited) momentum. While US Democrats sensibly try and absorb these "movement" impetuses (Hillary Clinton has maintained a solid lead over Bernie Sanders in the nomination race by not alienating most party members), the PLP demands the formation of a committee of public safety. The bilious McTernan believes that the expressive sets us on the road to the gulag: "The new politics is a movement politics – and movement politics, for all its avowed inclusivity, is a fuelled by insider/outsider demarcations. Once you understand that then everything else flows from it – stigmatise, isolate, eliminate. Just like the Bolsheviks used to say – fewer but better Russians".
Meanwhile, Nick Cohen continues to stigmatise, isolate and eliminate "the myth of leftwing decency". To this end we are told that "Leftwing men can treat women appallingly" (indeed they can, and so can chiropodists, Fulham fans and the left-handed); and that "Leftists would behave better if they stopped acting like teenage vegetarians and found the honesty to acknowledge their kinship with the rest of compromised humanity". The obligatory Orwell homage (those veggies presumably wear sandals) points to the continuing determination to cast the left as merely expressive, while the criticism of their assumed superiority ("they" think they are better than the rest of us) is textbook partisan.
In adopting a highly aggressive and emotional stance towards the left, the right of the Labour Party is acting partisanly, but in an American style. The problem is that they lack the "movement" necessary to support this. Having alienated the membership through their managerialism as much as their policies, they have come to rely on the patronage of the rightwing media as a proxy for popular backing. Similarly, in their belief that working class voters are itching to desert Labour and join the UKIP bandwagon, they are continuing to push the marketisation of British politics, in particular importing the American trope that the working class of the hinterland are inherently bigoted and resentful and must be placated by "tough" retail policies on security and welfare. It shouldn't come as any surprise then that the vocabulary of the Labour right is beginning to sound a little McCarthyite.