A pro-Jeremy Corbyn group is pushing for a change in Labour Party rules which could lead to Bristol West MP Thangam Debbonaire being deselected - just weeks after she secured one of the biggest majorities in the country.

The Bristol Post understands that several Momentum supporters are backing an amendment to the party's constitution at an extraordinary general meeting tonight. The change in how Labour selects its prospective parliamentary candidates would make it easier to challenge and potentially deselect sitting MPs. Several other Labour branches across the country are expected to back the amendment, with the aim of getting it debated at the Labour Party conference this autumn.

It is understood that Momentum is mounting a national effort to deselect more moderate Labour MPs to put more left-wingers into Parliament and ensure Jeremy Corbyn's eventual succession.

If passed at the conference – which is by no means a certainty – it would make it almost impossible for incumbent MPs to be reselected automatically.

Despite her incredible 37,336 majority, Ms Debbonaire would be vulnerable to a Momentum takeover due to her previous clashes with Mr Corbyn.

Ms Debbonaire would be permitted to finish her term in office if she was not reselected as a result of the new rules. But a different Labour candidate could then be put forward for the next general election in Bristol West, where Labour secured two thirds of all votes cast on June 8.

A party source, who asked not to be named, told the Bristol Post: "It's scandalous that a clique of Jeremy Corbyn supporters refuse to accept the huge mandate that Thangam received at the general election."

The current system means incumbent Labour MPs are rarely deselected. The normal process sees each Labour constituency hold a ‘trigger ballot’, where all local members are given the chance to vote on whether to endorse the sitting MP or to support the launch of a full selection process to open the race up to other candidates.

Trigger ballots almost always ensure that the incumbent MP is reselected.

However, if passed, the proposed amendment would see the trigger ballot process slightly change. Instead of each constituency member getting the option to vote, only members who attend a certain meeting would get the chance to vote. Moreover, the incumbent MP would be required to get two thirds of the overall vote to be automatically reselected.

The suspicion among moderates is that Momentum would flood each of the ballot meetings and force a full selection process to allow one of the group's preferred candidates to stand.

Ms Debbonaire had a public falling out with the Labour leader early last year, when she was told she had been appointed shadow arts and culture minister for six weeks before being told it was a “mistake”.

She then took part in a failed attempt to oust Mr Corbyn as leader of the party last summer.

However, since then she has served as a party whip for the Mr Corbyn and her attitude towards him appeared to soften in the election campaign.

While she may still be a target for Momentum supporters, Ms Debbonaire has shown that she is a force to be reckoned with.

She returned a 37,336 majority on June 8 – the fourth biggest in the UK as a whole – and attracted a total of 47,213 votes – the second largest number of Labour votes in the country. Her total represented 65.9 per cent of all votes cast in the Bristol West constituency on June 8.

It is understood that Ms Debbonaire is aware of the Bristol West extraordinary general meeting, but has declined to comment.

The Bristol Post has asked the Bristol and West of England Momentum group for a comment.