Headache for Ed Miliband as Labour orders Gisela Stuart to quit the Commons if she becomes mayoral candidate
Birmingham's mayoral contest risks becoming a massive headache for Ed Miliband after Labour's National Executive Committee ruled that any MP selected as a mayoral candidate for the party must stand down from the House of Commons.
It means Edgbaston MP Gisela Stuart could be ordered to quit as an MP, if she succeeds in her bid to become Labour's mayoral candidate.
That could mean a by-election in Edgbaston, a seat which Labour held with a majority of just 1,274 in 2010 - to the genuine astonishment of local Tories, who were confident of winning the former Conservative stronghold back.
But there's another alternative, which I think is a real possibility - that Ms Stuart, who's never been a fan of toeing party lines, would simply refuse to quit, plunging Labour into a damaging and pointless internal row.
It's worth noting that boundary changes and social changes mean Edgbaston isn't quite the natural Tory seat it once was (it returned Conservative MPs from 1898 to 1997).
But it's still widely believed that Ms Stuart, a bit of a maverick and unashamed Blairite, managed to hang on to Edgbaston in 2010 because of her ability to convince natural Conservatives to vote for her.
A by-election in the seat could mean Mr Miliband actually manages to lose a Labour seat to the Tories in the mid-term of a Tory-led government which has imposed massive spending cuts, presided over record unemployment and isn't yet able to boast that the economy has recovered.
If Birmingham voters do vote "yes" in a referendum on creating an elected mayor on May 3, Labour plans to send out ballot papers for activists to choose a mayoral candidate on May 25. The result, naming the party's candidate, will be declared on June 15.
While it's not clear when a by-election takes place, it would presumably be before the mayoral election on November 15. MPs are being ordered to resign from the Commons once they are selected as the candidate - not if and when they actually become mayor - and it's hard to imagine Edgbaston could be expected to go without an MP from the middle of June to the middle of November.
Ed could well be facing his by-election during the silly season, in the run-up to Labour's conference in Manchester in September, when speculation about his leadership (which has died down recently) could be an issue again.
Of course, the Labour NEC ruling means that Ms Stuart takes a real gamble in standing for mayor. If she becomes the candidate, she could end up losing the November election and losing her seat too.
And it also means that opponents - including Labour rivals - can accuse her of abandoning her constituents in a bid to become mayor.
The decision helps rival candidates including Sion Simon, the former Labour MP for Erdington, and Sir Albert Bore, the former council leader. NEC members include Tom Watson, the Labour MP for West Bromwich East who is a supporter of Mr Simon and no friend of Ms Stuart (he was close to Gordon Brown, she was not). The possibility of a link is nothing more than speculation on my part.
Mr Miliband's problems may go even deeper, however.
The fact is that Labour cannot force any MP to leave the Commons. And I don't believe Ms Stuart will go.
If she refused to stand down as an MP on being selected as mayoral candidate, the most Labour could do would be to remove the whip, effectively expelling her from the Parliamentary Labour Party. But this would leave them with a bizarre situation in which their candidate to become mayor of Birmingham had lost the whip in the Commons.
Perhaps its worth noting that Ken Livingstone continued as an MP for a year after being elected mayor of London (albeit as an independent). Boris Johnson quit as an MP shortly after being elected mayor of London, but continued as an MP for seven months after being selected as candidate.
Something else that's strange about the NEC's decision is that a candidate will be selected by postal voting, in a city where Labour has been hit by repeated allegations of postal voting fraud.
You still can't join the party in Ladywood or Perry Barr without someone physically seeing you - so the party can be sure you are a real person and not a figment of someone's imagination, invented to get an extra vote in a selection contest.