Labour was yesterday forced to cancel the launch of its by-election campaign in Glasgow East, one of the party’s safest seats, after the man set to become its candidate unexpectedly withdrew from the contest.

George Ryan, a Glasgow councillor who was the favourite to be selected, pulled out hours before local party members were due to hold a final meeting to make their choice.

The by-election, triggered by the sudden retirement due to ill-health of David Marshall, the sitting MP, should be an easy victory for Labour, which is defending a majority of 12,507.

However, with Gordon Brown’s standing in opinion polls at an all-time low, the Scottish Nationalists believe they are in with a chance of securing a victory on July 24.

The loss of Glasgow East would be more embarrassing than Labour’s failure to secure Crewe & Nantwich in May, where its majority of more than 7,000 was overturned by the Tories, or the debacle last month in Henley, where the party finished fifth behind the British National party.

Labour sources claim that Ryan withdrew his name from the contest because his “partner was concerned about the invasion of their private life”.

No 10 last night denied rumours that the prime minister had personally tried to persuade Steven Purcell, leader of Glasgow city council, to put his hat in the ring.

The party is now set to pick Margaret Curran, who is already a member of the Scottish parliament. If she is elected to Westminster, Labour will face a further risky by-election for her Holyrood seat.

Times Recommends

• Sarah Brown says 'no thanks' to veal at G8 - twice
• Stockton-on-Tees is obesity capital of Britain
• Stores blame poor sales on Murray factor