Colum Eastwood is to quit as leader of the SDLP, the PA news agency understands.
Mr Eastwood is expected to announce the decision when he “makes a personal statement” about his future on Thursday, a senior SDLP source said.
The MP for Foyle became the party’s youngest ever leader in 2015, having taken over from Alasdair McDonnell following a leadership contest that he won by fewer than 40 votes.
The 41-year-old father of two also previously served as the mayor of Derry.
While Mr Eastwood led the party as it consolidated its position in Westminster, the SDLP has failed to make progress at the Northern Ireland Assembly.
In the last Assembly elections in 2022, the party trailed in fifth – leaving it without a sufficient number of seats to be eligible for a place in the Northern Ireland Executive.
Claire Hanna, the MP for South Belfast and Mid Down, is considered to be among the front runners to be the new leader.
Ms Hanna currently acts as the party’s deputy leader.
Mr Eastwood was returned as the MP for the Foyle constituency at the beginning of July, claiming a majority of just over 4,000 votes.
At the time, he said: “I’m very grateful, mostly to the people of Derry, who have once again said that they want their voice to be heard in Westminster.
“I will gladly continue to be your voice. I will stand up for the people of our city, of our constituency. We won’t be quiet.”
Following reports of Mr Eastwood’s decision, former Northern Ireland secretary Julian Smith said on social media: “Really sorry to read that Colum Eastwood is stepping down from the SDLP.
“Whilst many differences on many issues, he is an exceptional communicator and I am certain will remain a key player in the UK and Ireland political fray. Ar aghaidh! [Forward!]”
SDLP councillor Seamas de Faoite said Mr Eastwood gave leadership and voice to the party’s vision and values “during the chaotic Brexit years”.
He added: “The foundation of the New Ireland Commission has helped us to chart a path towards a country free from the divisions of sectarianism, poverty and partition.
“Colum secured the first NI Assembly majority for Equal Marriage. He helped to bring about real progressive change in SDLP policy so we could truly be a party of Civil Rights again.
“He helped to bring forward more women, young people, LGBT+ and ethnic minority local leaders.”
Mr Eastwood’s decision to step down follows shortly after the announcement that UUP leader Doug Beattie will also be leaving his post.
