THE SDLP's share of Stormont seats will be cut by more than a third at next year's assembly election, an internal party report predicts.

A document compiled by SDLP headquarters shows leading party figures, including deputy leader Dolores Kelly and European election candidate Alex Attwood, will be among those who could fail to get re-elected.

The internal report, seen by The Irish News, makes predictions based on May's Westminster election result when the SDLP's share of the vote dropped by 2.6 per cent.

It forecasts that the party will hold its seats in the strongholds of Foyle and South Down, where it has three and two MLAs respectively.

However, in Alasdair McDonnell's Westminster constituency of South Belfast, where the leader was returned as an MP with the lowest ever share of the vote, the party will lose one of its two MLAs.

The report also predicts the loss of representation in North Belfast, where senior party figure Alban Maginness is the incumbent, and in East Derry, where current MLA John Dallat is not expected to stand again for election.

Overall the figures point to a poor assembly election performance with the party's Stormont seats cut from 14 to just nine.

In deputy leader Dolores Kelly's Upper Bann constituency, the SDLP is likely to lose out to Sinn Féin, while European Election candidate Alex Attwood's West Belfast seat is expected to be snatched by People Before Profit's Gerry Carroll, who received almost 7,000 votes in May's Westminster poll.

The report forecasts no gains for the party but it would hold its single seats in West Tyrone, Mid Ulster and Newry and Armagh.

If the predictions were to be realised it would mean the SDLP would be Stormont's fifth largest party – a far cry from 1998's assembly election when under John Hume it was second only to the UUP with 24 MLAs.

The document's contents are revealed just a week before Dr McDonnell attempts to fend off a leadership challenge at the SDLP's annual conference from Foyle MLA Colum Eastwood.

The 32-year-old launched his leadership bid at the end of September and with odds of at 4/9 he is the bookies' favourite to win.

South Belfast MLA and Dr McDonnell ally Fearghal McKinney is also challenging Mrs Kelly for the deputy leader's post.

In recent weeks senior party figures past and present have backed Mr Eastwood's campaign.

Those who have endorsed the Foyle MLA include one-time Deputy First Minister Seamus Mallon, former SDLP deputy leader Brid Rodgers and Foyle MP Mark Durkan, who led the party for nine years up to 2010.

Earlier this week, Dr McDonnell said he was confident of victory on November 14.

"I won the leadership by a handful of votes and I will win it again by a bigger handful of votes," he said.