Sultana, 31, who represents Coventry South, posted a statement on Thursday evening describing Westminster as “broken” and claiming the two main parties offer “nothing but managed decline and broken promises”.
She urged supporters to “join us” in creating what she presented as a new party.
Her declaration took some in the alliance by surprise and has exposed divisions over strategy. While Corbyn has long hinted at plans to establish a more organised vehicle for leftwing and pro-Palestinian campaigning, he has so far avoided confirming any formal structure or leadership arrangements.
Corbyn, 76, has not committed to the project becoming a party, or endorsed any specific leadership roles. The Guardian understands he was frustrated by Sultana’s unilateral announcement, which some regard as premature and potentially counterproductive.
So far, he has confined his public comments to cautious remarks about the group “coming together” and “offering an alternative”, without outlining further details.