Birmingham Labour MP Roger Godsiff is facing claims that his General Election victory was marred by vote-rigging.
A petition lodged at the High Court by losing Respect Party candidate Salma Yaqoob alleges that widespread fraud took place in the Sparkbrook and Small Heath constituency, where Mr Godsiff saw his 16,246 majority cut to 3,289.
The 24 per cent swing against Labour, one of the highest in the country, came off the back of a strong anti-Iraq war and pro-immigration campaign by Ms Yaqoob, who was the runner-up.
The constituency includes Bordesley Green, where an election court earlier this year found three Labour Birmingham city councillors responsible for conducting a campaign of postal vote fraud. The three were expelled from the council and 19 Labour supporters were also named in court as having taken part in corruption.
Ms Yaqoob plans to present evidence demonstrating how people who arrived at polling stations to vote at the General Election were turned away because someone had applied for and used a postal vote in their name.
Others attempted to vote only to be told that someone else had already voted in their name, Ms Yaqoob added.
Mr Godsiff, who denounced postal vote fraud in a speech to the House of Commons shortly after the June 2004 council elections, has already made clear his suspicion that malpractice may have occurred during last month's General Election.
Mr Godsiff said at the time: "There have been people who have come here and been told that they have got a postal vote. Also a lot of postal votes appear not to have reached people.
"People are being denied the right to vote and this is a cause for concern and should be investigated."
Ms Yaqoob now faces a difficult task in collecting evidence to persuade a judge to order an election court to be held in Birmingham. The court could overturn the Sparkbrook and Small Heath result, order a fresh election or declare Ms Yaqoob the winner.