Labour is battling to prevent its annual conference from descending into bitter infighting after Jeremy Corbyn was forced to defuse an attempt to oust the party’s deputy leader and faced fresh anger over Brexit.

As the party gathered in Brighton on Saturday for its annual gathering, the Labour leader intervened to halt a surprise attempt to remove Tom Watson and abolish his deputy leader post. His decision came after an outcry from MPs, shadow ministers, officials and union leaders.

The row, which erupted on Friday night, plunged the party into a significant crisis as its conference began. At a meeting of Labour’s ruling national executive committee (NEC) on Saturday morning, Corbyn instead proposed a review of the deputy leader post, which was accepted by the group.

Play Video 0:56 Jeremy Corbyn: I enjoy working with Tom Watson – video

The attempt to oust Watson, who has been pushing Labour to have a more pro-remain Brexit policy, was launched late on Friday night by Jon Lansman, the leader of the pro-Corbyn Momentum group. Lansman tweeted that he agreed with Corbyn’s proposal. “We need to make sure the deputy leader role is properly accountable to the membership while also unifying the party at conference,” he said. “In my view, this review is absolutely the best way of doing that.”

Asked on Saturday morning whether he had known about the plan to oust Watson, Corbyn said: “The NEC agreed this morning that we are going to consult on the future of diversifying the deputy leadership position to reflect the diversity of our society. And the conference will move on to defeating austerity, to the green industrial revolution, green new deal that we are putting forward and giving the people a final say on Brexit. Our NEC left this morning in a happy and united mood.

“Our conference will be totally united on defeating this Tory government and the austerity and poverty they have brought to the British people, and the way in which the prime minister has shut down parliament to prevent accountability and debate. That’s not the Labour way. We’ll do things very differently.”

Profile Who is Tom Watson? Show Hide Tom Watson, who has been Labour’s deputy leader since 2015, has been an MP since 2001. The 52-year-old served as a minister in the Labour government and was appointed the deputy chair of the NEC by Ed Miliband.

Watson stepped in to personally handle complaints in the midst of Labour’s antisemitism crisis. He backed automatic exclusion of members accused of anti-Jewish racism. Earlier this year, Watson called on centrist MPs to stay and fight within the Labour party, putting an end to rumours he would lead a split of centrist Labour MPs. In his speech earlier this month, Watson said his party must “unambiguously and unequivocally back remain” in a second referendum, a move that Jeremy Corbyn believes to be the wrong approach. As well as regularly being in conflict with the Labour leadership, Watson has had a long-running feud with Len McCluskey, the general secretary of Unite, Labour’s biggest donor. The pair, who were once close friends, have clashed over Corbyn’s leadership and Brexit. Watson said he was in a Chinese restaurant in Manchester when he heard of the motion to scrap his position within the Labour party. He described the move as a “straight sectarian attack on a broad church party”, adding it was “a sort of sleight of hand of constitutional change to do a drive-by shooting of someone you disagree with on the issue of the day.”

The attempt to remove Watson, who was unable to defend himself at the meeting, immediately reopened the debate among MPs about what they should do if the ambush succeeded. Talk of splits and defections immediately returned, with several Labour sources saying that more departures were now more likely.

The leaders of Unison and the GMB, two of the three big unions affiliated to Labour, immediately attacked the attempt to remove Watson.

However, while Corbyn managed to postpone a row over Watson’s position, he was immediately facing pressure over Brexit as it emerged the party was planning to decide its final position on the issue after the next election.

A draft motion, circulated among the NEC on Saturday but not finally agreed, called for a special conference to be called after the election to decide whether Labour should back a Brexit deal it had negotiated, or back staying in the EU.

The Labour MP Lloyd Russell-Moyle said: “Why would the NEC call for a special conference on Brexit when we have the actual conference this week. We cannot support kicking the can down the road longer, we are at the cliff edge. Party democracy must be respected and conference must get a vote on campaigning to remain.”

Profile Who is Jon Lansman? Show Hide A 62-year-old Labour veteran who joined the party in 1974 and worked for Labour icon Tony Benn during his deputy leadership campaign in the 1980s. Lansman served as director of operations for Corbyn’s leadership campaign. After Corbyn was elected as the leader of the Labour party in 2015, Lansman founded Momentum, a pro-Corbyn campaign group.

Momentum, often described as a ‘party within a party’, has radically transformed the Labour party over the last four years. Local groups have challenged party orthodoxies and national membership rules, and fought to get their activists selected. “I don’t want the Labour party to become a faction fight,” Lansman said in a 2016 interview with the Guardian. “What I want is a level playing field. I want the Labour party to be able to have a democratic debate.” But in recent weeks, Lansman, and Momentum, are back in the news for being key figures behind another Labour party civil war. Lansman was behind the move to scrap Labour’s 40-year-old student wing, arguing the group needs reforming and had not paid its affiliation fees. Critics described the move as a cynical attempt to shut down a “moderate” wing of the party. Lansman also tabled a last-minute motion at the NEC last year calling for deputy leader Tom Watson’s job to be scrapped. The motion was withdrawn after Corbyn intervened.

Watson described the attempt to out him as a “drive-by shooting”.

Speaking to BBC Radio 4’s Today programme, he said: “I got a text message in a Chinese restaurant in Manchester to say that they were abolishing me.

“It’s a straight sectarian attack on a broad church party and it’s moving us into a different kind of institution where pluralism isn’t tolerated, where factional observance has to be adhered to completely and it kind of completely goes against the sort of traditions that the Labour party has had for 100 years.”

Senior Labour figures came to Watson’s defence. The former prime minister Tony Blair said a decision to abolish the post of deputy leader would be “undemocratic, damaging and politically dangerous”.

He added: “To suggest it at this time shows a quite extraordinary level of destructive sectarianism. The Labour party has always contained different views within it and the deputy leader’s position has been one way of accommodating such views.

“Getting rid of it would be a signal that such pluralism of views was coming to an end despite being cherished throughout Labour’s history.”

The former Labour leader Ed Miliband said: “The move to abolish the deputy leader post without warning or debate is undemocratic, wrong and should not happen. Those who came up with the idea for the eve of Labour conference have taken leave of their senses.”