Ladbrokes shortened Labour's odds in the Glasgow East by-election yesterday to make the party joint favourite with the SNP to win the seat at 5/6.

For Labour, who failed to select a candidate last night, that could be just a temporary improvement in fortunes. When the gun was fired on this three-week steeplechase the SNP were 8/13 on. But don't place your money until you hear the apocryphal tale of the election agent encountered in the street during one campaign with a large wad of banknotes protruding from his sports jacket.

His plan was simple. Having collected £1000, a sizeable sum, from committed supporters, he was hotfooting it to the local betting shop to skew the odds so wildly that there could be no comeback for the opposition. It was one week out from the vote and the agent reckoned timing was everything. He was right - once the money was over the counter all bets were off and the agent's man was the bookie's surefire winner.

If only by-elections could be predicted with the certainty of bookie's odds. No-one dares stake their reputation on the outcome of the Glasgow East and last night's events - when Labour postponed it's selection process - showed how dangerous it is too take a punt too early.

It is understood that the favourite for the Labour nomination, Shettleston councillor George Ryan, was unable to attend the constituency selection meeting. His partner is apparently reluctant for him to seek the nomination.

Understandable domestic pressures interupting a political career is something of a theme this week and comparisons will be made with Nicol Stephen, who resigned as Scottish Liberal Democrat leader to spend more time with his family.

However Mr Ryan's and Labour's circumstances are resolved the postponement is the worst start the party could have for the campaign and a bad omen for what is predicted to be a bitter contest.

David Marshall's former seat should be safe Labour territory - a 13,500 majority, the third-safest in Scotland - but now it is being treated not so much as a litmus test, more as an acid bath, for Gordon Brown's premiership.

Unlike Crewe and Nantwich or Henley this is not a slow-motion car crash for the government. To lose in Glasgow East would be a politically cataclysmic, an earthquake on a scale to shake Mr Brown out of Downing Street.

To win the seat, the SNP would need a 21.9% swing but Alex Salmond is not one to say anything is beyond him. The First Minister will be in the constituency today and on Monday for the official SNP campaign launch. Their candidate, councillor John Mason, has represented the Ballieston ward on Glasgow council, covering one-third of the constituency, for the last decade.