ANY question of the recent opinion poll pressure that Labour has come under in Scotland being a flash in the pan is dispelled by latest System Three poll for The Herald.

Dramatically, it puts the SNP 5% ahead of Labour in terms of voting intentions for a Scottish Parliament.

If voters cast votes in the first and second ballots in the same manner this time next year, then it would see the SNP come within one seat of becoming the single largest party.

The SNP would take 52 seats, with Labour one ahead on 53. It would also mean that Labour's ability to govern Scotland, even in coalition, would be put in doubt. To achieve an overall majority in Holyrood, the target is 65 seats. Labour would only just achieve this in combination with the Liberal Democrats' projected 12 seats.

Despite the public face put on the worsening situation in Scotland, privately Labour workers must have their heads in their hands. A matter of eight months has seen any Labour advantage from September's referendum disappear. Yet Labour retains a 14% advantage on voting intentions for Westminster.

What is even more puzzling for Labour's national leadership is that all this falls within a context of Labour performing better across Britain than it did in the General Election a year ago, and British-wide opinion polls indicating the Blair Government as the most popular post-war administration.

Current opinion poll indicators would have Labour with a massive 250-seat majority in Westminster.

So what has gone wrong for Labour in Scotland? The answer lies in what appears to be a new dominant two-party system emerging in Scotland - at least in the context of the Scottish Parliament. Although the Conservatives show a modest rise this month, and Liberal Democrats are holding their own, these two parties cannot sustain more than a quarter of Scottish votes.

As a consequence, if the Scottish Parliament elections are seen as a question of who runs Scotland, then Labour and the SNP dominate. Here, voters are split not only on party choice, but as the weekend's ICM survey indicated, also on which party leader is best to lead Scotland. Donald Dewar and Alex Salmond are neck and neck with 40% and 41% respectively. Additionally, with almost as many voters saying Labour is not standing up for Scotland (41%), Labour has a credibility gap.

The vote share suggests that this split is becoming more apparent and, crucially, is beginning to have an impact in Scotland's Central Belt.

In the constituency ballot for a Scottish Parliament - if votes were cast according to the System Three survey - then the SNP would finally begin to make a breakthrough, taking seats such as Livingston, Linlithgow, Midlothian, Dumbarton, Edinburgh North, and Leith.

The shielding that Labour receives from the first-past-the-post element of the ballot is not to be underestimated. With Labour 5% behind the SNP, it still would take 42 constituency seats against the SNP's 23. If the SNP managed to concentrate its effort and consolidate these current shifts in support, then Labour would be in further difficulty.

Perhaps Labour has failed to gauge exactly how much Scottish politics has become just that - Scottish politics. If so, then it is running the risk of losing further ground.

It cannot simply ignore the message now, so expect to see more vociferous attacks on the SNP.

Malcolm Dickson is a lecturer in politics at Strathclyde University