Ken Livingstone’s support for an alleged Islamist extremist-backed candidate and his “divisive” approach to politics has undermined his support on the Labour frontbench, HuffPost UK can disclose.

In an interview with this site, Shadow minister Rushanara Ali says that following Livingstone’s decision to campaign for independent candidate Lutfur Rahman as the elected mayor of Tower Hamlets, she and activists would withdraw her support from Livingstone if he “behaves the way he did previously.”

Ali, the MP for Bethnal Green and Bow, is considered a rising star in the Labour party. She said Livingstone backing Rahman a year ago was “completely unacceptable” and he should “know better”.

Rahman, who was de-selected as Labour’s candidate for the mayor of Tower Hamlets following accusations about his links to a fundamentalist Islam group, stood and won as an independent in 2010 - with support from Ken Livingstone, who had just been selected as Labour’s mayoral candidate, beating out Oona King for the role.

Rushanara Ali tells Huffpost UK: “The entire national executive and the Labour party, nobody was happy about his behaviour. He should know better. He is a leading member of the Labour party with a high profile, and coming into my constituency and the borough of Tower Hamlets and playing divisive politics, essentially not backing-up your party at a very difficult time, was a low point in his recent political activity.”

Click here to read the full interview.

With the Mayoral election expected to be closer than current polling suggests, the support of communities in east London will be crucial to Labour’s campaign, particularly when the East End has a track record in favouring independent candidates such as George Galloway and Lutfur Rahman.

She said while she was currently campaigning for Livingstone, “that support is of course conditional. If he behaves the way he did previously, in the last executive mayoral election where he couldn’t even support his own party’s candidate, then there will be plenty of people on the ground that will not feel motivated to campaign for him.

“And it’s very difficult for us, however much we may try, to mobilise and activate our activists and constituents if that kind of confusion is created again.”

But Ali, who used to work for Oona King, maintained that “in the end” Ken’s politics won out: “Taking aside that particular low point where we suffered politically. In terms of the substantive action he took, that says a lot about his time as mayor that benefited my constituency and of course that’s what I’m focused on.”

HuffPost UK put Rushanara Ali's points to Ken Livingstone and we're awaiting a response.