Row brews over lack of access to members’ data that some say favours Rebecca Long-Bailey

MPs supporting Keir Starmer and Lisa Nandy in Labour’s leadership battle have accused the party’s hierarchy of handing fellow candidate Rebecca Long-Bailey an advantage by preventing parliamentarians from contacting constituency members.

All Labour MPs have been told they are not allowed to contact their members using Labour party data; but an outside organisation, such as the grassroots group Momentum, can contact theirs – even though there is much overlap.

While Long-Bailey’s campaign is backed by Momentum with its large database of Labour members, Starmer and Nandy’s supporters in parliament say they cannot send literature to members explaining who they will support.

It is the first time that MPs have been warned not to contact their own constituents during a leadership election campaign. Starmer received 88 nominations from MPs, Nandy received 31, while Long-Bailey received 33.

The development reflects tensions between rival wings of the party – and supporters of the four remaining candidates for the leadership – over the conduct of the contest, which comes after Labour’s worst general election result since 1935.

Clive Betts, the chair of the housing select committee who nominated the current favourite Starmer, said there is “a lack of even handedness” in the way the party has made decisions over the leadership battle.

“Momentum have got their information and they are using it. As an MP, I have got to have the right to communicate my views to my constituency’s members during a crucial election. We can’t have a discussion about what went wrong in the election without talking about individuals.

“It is wrong that the party sent out these rules without having a discussion with the parliamentary Labour party first,” he said.

Tulip Siddiq, the MP for Hampstead and Kilburn and a Starmer supporter, said: “My local members are some of the most engaged in the country – if I take a shower I get emails asking how hot it was – so to not be able to communicate my own feelings to those members who I work with on the biggest decision facing the party for years is staggering.”

Vicky Foxcroft, the MP for Lewisham Deptford and a Nandy supporter, said: “There is only one membership list that can be used at the moment and it’s the Momentum one, and only one team has access to it.

“We want more democracy and to make people accountable whilst choosing our next leader. But without membership lists with which you can communicate with members, how are we supposed to have those important conversations?” she said.

In an email sent on 6 January from Labour HQ, MPs were warned that “elected representatives or their staff must not use their access to members contact information to communicate about the election including the promotion of a preferred candidate. Any breach of this may result in a sanction determined by the procedure committee.”

Momentum, which has 40,000 activist members, endorsed Long-Bailey last month and has already contacted its members urging them to back her.

The MP for Salford and Eccles is widely believed to have the backing of the current leader, Jeremy Corbyn, and has secured the support of the UK’s second biggest union, Unite. She now needs the backing of one more union or affiliated society to make it on to the ballot paper with Starmer and Nandy.

The fourth contender, Emily Thornberry, is trying to use the other route on to the ballot paper, by gaining the support of 33 constituency Labour parties (CLPs).

The party’s membership data will be distributed among the candidates who reach the final ballot on 15 February. A winner will be declared in April.

A Long-Bailey ally said: “Any organisation such as a trade union or Labour First that endorses a candidate is permitted to use any data they hold.”

Party insiders said the restrictions imposed on MPs contacting constituents was in response to data laws, and applied to all leadership candidates.

A Labour spokesman said: “The rules and conduct of the leader and deputy leader elections have been designed to be fair to all candidates, and as open and democratic as possible.”

A party source also said that a recent minor rule change meant that MPs were able to send a short email to their local party members explaining who they had nominated, but were not allowed to give reasons why.