LONDON—Jeremy Corbyn’s socialist leadership team—which includes anti-war campaigners, young activists, and former communists—is on the verge of seizing full control of Britain’s Labour Party for the first time.

A brief post-general-election ceasefire is over, and voters head to the polls for local elections on Thursday with Labour gripped once more by civil war.

Recent criticism of Corbyn’s handling of anti-Semitism accusations and his response to the poisoning of a former Russian spy in Salisbury have renewed the Left’s desire to clean out the centrist Members of Parliament (MPs), who refuse to back the leader and continue to attack him in public.

The vast majority of Labour’s MPs did not support Corbyn’s bid for the leadership, which promised a decisive break from the legacy of the party’s most successful prime minister, Tony Blair.

One of the key lieutenants from Corbyn’s personal 2017 election team says he—and many on the Left—have previously resisted calls to support “bloodletting” in the party but he now believes a handful of “utterly intransigent” centrist MPs may need to be forced out to instil unity.

“There are people who need to be held to account for what they’re doing,” Steve Howell, Corbyn’s former deputy director of strategy and communications, told The Daily Beast. “The party can’t progress when these kind of negative, divisive activities are taking place at every turn.”

It is incredibly rare for any sitting politician to be effectively “primaried” in British politics—and there is no real culture of open contests for party nominations. The prospect of deselecting sitting MPs or having them thrown out of the party via disciplinary procedures would mark a dramatic escalation in an internal conflict that had been suspended after Corbyn performed better than expected during last year’s election.

Howell has written an account of the campaign from the perspective of Corbyn’s small team called Game Changer: Eight Weeks that Transformed British Politics. In it, he describes the way initial difficulties in implementing the campaign because of a disunited party structure melted away as they got closer to polling day and MPs and Labour apparatchiks accepted that Corbyn was surging in the polls.

He believes that this transformation will continue with the whole party uniting behind Corbyn—whether by choice or under pressure—allowing a genuinely left-wing, socialist party to emerge from the remains of one of the world’s great social democratic parties.

British media typically portrays this revolution as a purge of the moderates, but the Left argues that it’s the centrist MPs who are refusing to accept political norms; they reject Corbyn’s authority as leader even though he was twice elected by the party members.

Howell—and his left-wing colleagues—say the Labour MPs must do a better job of reflecting the views of the grassroots party membership, which was swollen by the campaign to elect Corbyn as the most radical leader in Labour’s history.

Ian Lavery, who was appointed Labour Party chairman by Corbyn last year, agrees that Labour MPs should be beholden to the party membership, reminding them that the system of “trigger ballots” allows local parties to fire MPs who are acting out of line.

“This shouldn’t be a job for life. Sometimes you’ve got to represent the views of your constituents against your own wishes,” he told The Daily Beast. “MPs will obviously make their choice.”

Howell has been a member of the Labour Party for more than 20 years, but some observers say you need to delve deeper into his political heritage in order to understand where he and his fellow luminaries on the Left want to see the party.

He recalled his years in the Communist Party in the 1970s and ’80s: “The Communist Party’s politics stretched from Marxist socialist in its classical sense—which I would consider myself to be, frankly—to a large swathe of people whose politics was no different from Roy Jenkins or David Owen who ended up merging with the Liberal Democrats.”

In other words, he says he wasn’t on the woolly, right wing of the Communist Party.

The former activist was invited to join Corbyn’s core team by Seumas Milne, whom he knew from decades of campaigning on the Left. Milne is Corbyn’s top political adviser, strategist, spokesman, and right-hand man—he is also a former Guardian columnist with a long history of communist-sympathetic columns including support for the late Venezuelan strongman Hugo Chávez and Fidel Castro. He also raised questions about the reported size of death tolls under Mao and Stalin.

Howell was first introduced to Milne in the early 1980s by Andrew Murray who was writing for the communist daily newspaper The Morning Star at the time.

Milne put the old gang back together last year when Murray was seconded from Britain’s largest trade union, Unite, to the Labour election team just five months after Murray quit the Communist Party.

Howell had gotten the call from Milne in January 2017. Together this small cadre of Corbyn supporters was tasked with helping to reshape the policy and communications operation of a party whose structure was still made up predominantly of center-left professionals and politicians.

Prime Minister Theresa May called a shock snap election just two months after Howell had started work in Corbyn’s office. Under British election rules, the leader’s staff was forced to leave their office overlooking the Thames on the parliamentary estate and move into the party offices in Southside. In his book on the campaign, Howell described the moment the two sides came face-to-face. “Some seemed intrigued by the invading Corbynistas, as if we had landed from Mars. A few—only a handful—could barely conceal their disdain,” he wrote.

Bit by bit, the Corbynistas have won over the doubters—or forced them out, including Iain McNicoll who lasted until February when he resigned as general secretary of the Labour Party.

Lavery, who became a Labour MP after eight years at the head of the National Union of Miners, where he succeeded Arthur Scargill, was an early supporter of Corbyn for the leadership and he now welcomes fresh input into the party from the broad Left.

“Being a communist at some stage in your life certainly doesn’t mean you shouldn’t be part of the Labour Party. I mean the Communist Party support the Labour Party, that’s the reality of it,” he told The Daily Beast.

They’ve only supported Labour since Corbyn took over, of course. At the 2017 election, the Communist Party decided not to run any candidates of its own for the first time since 1920, urging members to vote Corbyn into Downing Street as “the first step towards a formation of left-led government at Westminster.”

Labour contested the election on a platform of nationalizing the railways, postal service, and utilities and increasing tax on the highest earners but it was hardly a communist manifesto. In fact, it was extremely popular.

“If they try and broadcast or present communism as an alternative, nobody’s going to buy that,” a veteran Labour MP and former minister told The Daily Beast.

Instead the leadership team is working to tarnish capitalism, highlighting the vast inequality in Britain and attacking the lack of regulation.

The former minister claimed Corbyn was “not clever enough” to deliver this strategy himself, but said fellow veteran of the Left, John McDonnell, the shadow chancellor, was the real danger.

“What they believe is tearing the system down and replacing it with something entirely different—akin to communism—which most of us know is never going to work. I’m convinced that they actually do believe that it might work in a more modern setting—with a more modern application and using the city of London to finance it,” he said.

“The communists are interested in using Jeremy… They are staffing up the leaders office with people who agree with the project and party headquarters. They have captured the party ideologically—we are no longer the Labour Party. I think most people inside the party recognize that.”

Steve Howell and Ian Lavery argue that there is also a far simpler reason to bring the party together ideologically: It’s much easier to campaign with one voice.

Howell described the frustration of waiting hours for both the leaders’ office and the party HQ to sign off on every press release, or agreeing to the allocation of resources from central funds.

From the outset, the Corbynistas were confident that money should be spent on attacking Conservative-held seats while the party elders thought the focus should be on defending their existing seats because of poll numbers that had Theresa May as much as 24 points ahead. Of Corbyn’s first 48 campaign stops, only 20 were in Labour-held districts, and yet the central party money was being funneled to totally different areas.

Even later in the campaign when the polls were improving for Labour, Howell says: “They were just utterly convinced that the polls were wrong and we [Corbyn’s leadership team] were in La-La Land.”

Lavery, who was installed as Labour’s election coordinator, said it took time for the party staff to get used to the new ideas and the new way of doing things under Corbyn. Gone were most of the carefully stage-managed Blair-era chatshow interviews and the triangulated messaging for middle Britain.

“It was a huge change for our people. Quite often there were delays but that’s just part of the coming together,” he said. “Aye, it was at times frustrating but nobody ever said that the struggle was easy. It’s not called the struggle for nothing, you know.”

Ahead of the vote, virtually all outside observers expected Corbyn to be vanquished by May, who had called the election hoping to secure a huge majority in the House of Commons to ease the passage of Brexit. In the event, Corbyn’s election campaign electrified young voters and re-energized old Labour supporters who united to stop May winning the election outright.

Although he still lost, it was that unexpected election result that cemented Corbyn’s position at the head of the party and gave his acolytes the chance to rebuild it in his image.

One of the reasons for Corbyn’s popularity was his refusal to listen to his centrist party colleagues who said he must moderate his message. “Jeremy was challenging not only seven years of Tory austerity but also the neo-liberal orthodoxy that had been entrenched since the Reagan-Thatcher era,” said Howell. “As far as we were concerned, it would be from the outset a Labour campaign like no other.”

One other campaign that did provide inspiration was Bernie Sanders’ run for the Democratic nomination—another left-wing outsider taking on his own party. Early on Howell and Milne discussed the language they could borrow from the Vermont senator’s upstart campaign. Main St. vs. Wall St. didn’t pass the language barrier, but the idea of a “rigged” system became a mainstay of the Corbyn campaign.

The focus on rallies was another idea that was adopted. Labour under Tony Blair and Gordon Brown was very sceptical of rallies, usually opting for contained events with hand-picked crowds.

“We wanted to do big rallies of the Sanders type. They had an impact beyond the people who attended because they would be seen to be creating a buzz, and they would have a very visual impact on social media and online,” said Howell.

Having torn up the Blairite campaign book and published a radical party platform, Corbyn’s team had led Labour to the party’s biggest jump in vote share between elections since 1945. They had proof that their strategy could generate some success—now they reasoned that they would have done even better if the centrist Labour MPs hadn’t been talking Corbyn down or constantly trying to replace him.

“For Labour, there can be no going back,” concludes Howell in his book. He told The Daily Beast that he thought the party would be more united by the next election. As well as trigger ballots to primary centrist MPs, he raised the prospect of Labour’s National Executive Committee, with its newly installed pro-Corbyn majority, being able to expel MPs for bringing the party into disrepute if they continue to attack the leadership.

He hopes other veterans of the bygone era will give up the fight. “You would hope some of them would bow out gracefully, let’s put it that way,” Howell said.

If MP Ian Austin, a veteran of the Blair-Brown administrations, is anything to go by, that may be a forlorn hope. Asked if he was willing to heed Howell’s advice, he said: “You can quote me saying; ‘I’ve got no interest in anything this man has ever said.’”