Keir Starmer is preparing to support a purge of far-left factions that were vocal supporters of Jeremy Corbyn’s leadership.

After 15 months of being party leader, Starmer is expected to support a proposal before the party’s governing body on Tuesday to proscribe four named groups.

The proposal, first reported in the Daily Mirror, has angered leftwing members who believe this may be part of a wider purge of the party.

Labour’s ruling National Executive Committee will be asked to proscribe Resist and Labour Against the Witchhunt, which claims antisemitism allegations were politically motivated, and Labour In Exile Network, which expressly welcomes expelled or suspended members.

Socialist Appeal, a group that describes itself as a Marxist voice of Labour and youth, would also become a banned group. Anyone found to be a member of any these groups could be automatic expelled from the Labour party.

Several left-leaning groups are organising a picket of the NEC meeting at Southside, Labour’s headquarters in Victoria, central London, to protest against the proposals.

Norman Thomas, who founded the Labour In Exile Network, said in a statement: “There is wide agreement Starmer is pretty pathetic at fighting the Tories, but he’s in overdrive when it comes to attacking his own members. He has destroyed democracy in Labour to get rid of the thousands of people who joined after Jeremy Corbyn became leader.”

The move sets the stage for factional warfare at the Labour party conference in Brighton as Starmer attempts to stamp his authority on the party.

Thomas said there would be more action to come – including at the conference in September. “This is just the beginning of the fightback. We are fighting for the future of the Labour party,” he said.

A Labour spokesperson said: “Labour is a broad, welcoming and democratic party and we are committed to ensuring it stays that way. From time to time, there are groups the NEC will proscribe. The NEC will be asked on Tuesday to consider whether these four organisations are compatible with Labour’s rules or our aims and values.”

A number of prominent former members have been suspended in recent months.

Corbyn was suspended from the party in October last year for saying the problem of antisemitism within Labour was “dramatically overstated for political reasons” by opponents and the media. A disciplinary panel of the NEC lifted the suspension the following month after he issued a conciliatory statement but Keir Starmer refused to restore the whip to Corbyn.

Howard Beckett, a member of the NEC, was suspended from the party in May after he called for the home secretary, Priti Patel, to be deported on Twitter. The tweet, in response to an attempt to deport two asylum seekers in Glasgow, read: “Priti Patel should be deported, not refugees. She can go along with anyone else who supports institutional racism. She is disgusting.” Beckett, a leadership candidate for the Unite trade union before pulling out of the race, apologised and deleted the tweet.

MPs from Labour’s left have reacted angrily to the latest proposals, with the former shadow chancellor John McDonnell calling instead for the formal publication of the Forde Inquiry’s report on Labour’s internal handling of antisemitism complaints. McDonnell tweeted: “Standard Blairite fare to try show how strong a leader you are by taking on your own party but bizarre to do it by expelling people, most of whom have left already. Looks desperate when what is needed is restoration of whip to Jeremy Corbyn, publication of Ford [sic] & taking on Tories.”