By Alex Stevenson
Bradford West MP Marsha Singh is to step down from parliament after a period of serious ill health.
The Labour party said Mr Singh, 57, had decided to follow medical advice and step down from his seat after 15 years representing Bradford in the Commons.
"This is a sad day for me," Mr Singh said.
"I have been suffering with serious health problems for some months now.
"I have had wonderful treatment from our fantastic NHS doctors and nurses here in Bradford. But it has become clear that it is going to take much longer than I'd expected to recover."
Labour leader Ed Miliband paid tribute to Mr Singh, saying he had "stood up for social justice" and would be "greatly missed by his parliamentary colleagues".
His departure will trigger a by-election which Labour can confidently expected to win. Mr Singh secured a 2.9% swing in his favour at the 2010 general election, against the national trend, to improve his majority to 14.2%.
This will be the seventh by-election since May 2010 - and the sixth in a Labour-held seat. The party has not yet failed to hold any of the contested constituencies.
Another potential by-election possibility is Falkirk, the seat of Labour backbencher Eric Joyce. His local party is currently debating what steps to take against him after his violent altercation in a Commons bar last month left him suspended from the Labour party pending court proceedings.
Mr Joyce suffered a seven per cent swing away from Labour to the SNP in 2010, but maintains a majority of over 15%. It is thought local party members will back Mr Miliband's position rather than force him to resign, however.