A Labour heavyweight has put himself forward for the crucial Copeland by-election

LONDON - Former Labour MP Thomas Docherty has officially put his name forward to stand for the party in the upcoming by-election in Copeland.

The former MP for Dunfermline and West Fife, who was born in west Cumbria and worked there before entering into Westminster politics, confirmed to Business Insider on Monday that he has applied to be Labour's choice in the crucial upcoming fight to prevent the Conservatives claiming the seat for the first time ever.

The date of the by-election will be confirmed as soon as outgoing Labour MP Jamie formally triggers his resignation. Business insider understands itn is likely to take place in May in order to coincide with local elections, although March is also currently being considered.

Applications to stand for Labour closed on Monday.

Docherty is set to the biggest name in the hat, having previously held a number of junior shadow positions during Ed Miliband's leadership, including shadow deputy leader of the House of Commons. He and the other hopefuls will travel to London on Thursday, where they will be interviewed by the party's NEC. The NEC will then put together a shortlist of candidates from which the Copeland Labour Party will select its candidate on January 19.

The by-election will be a huge test of both Jeremy Corbyn's leadership and the party's relevance in working-class, pro-Leave seats like Copeland. Labour's majority was reduced to just over 2,500 votes at the last election, and bookmakers make the Tories' odds on to win the seat that Labour has controlled since 1931.

Senior Labour sources told us last week that both Corbyn and shadow business secretary Clive Lewis are set to make the trip up to Cumbria from London in the coming weeks, while Business Insider understands that activists from pro-Corbyn group Momentum visited the area over the weekend to do some campaigning.

Docherty's experience plus his links to the area make him a strong candidate in the contest to be Labour's Copeland candidate. Business Insider understands that a number of local councillors have told the former MP that they intend to back him, assuming he makes it onto the final shortlist as expected. Other names to look out for are well-respected local councillor Gillian Troughton and charity worker Rachel Holliday.

The latter has been dubbed as an early favourite but her support for Corbyn in the party's last leadership election could be an issue in an area so reliant on the nuclear industry. Holliday describes herself as centre-left and pro-nuclear, but she will have to distance herself further than Corbyn in order to optimise her chances of being selected. The Conservatives have already begun distributing leaflets in the area linking whoever runs for Labour with Corbyn's anti-nuclear position. The fact that Momentum members from London have already visited the area will only give the Tories more ammunition to use against whoever is chosen to try and retain the traditional Labour seat.

Troughton lacks name value but is a respected champion for local causes, including the under-pressure West Cumberland hospital. As a local activist told Business Insider last week:"She's [Troughton] local... She has a strong handle on the big issues in the seat. I can only see them going for an out of towner if the locals put forward are genuinely hopeless. Cumbrians don't like people coming from across the country and telling them how to do things."

A full list of people who have applied to stand for Labour is set to be published by Tuesday.