Blair urged to quit early as Scottish poll disaster looms

The survey reveals that the Scottish Nationalists are on course to oust Labour as the largest party in the Holyrood Parliament.

Defeat in his Scottish power base would be a disaster for Gordon Brown as he prepares to succeed as Prime Minister.

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This weekend senior Labour figures are privately urging Mr Blair to bring forward his resignation to before polling day on May 3, when his party also faces a rout in the Welsh Assembly and English council elections.

A senior aide said: "If Tony sets out an exit timetable before Scotland goes to the polls, then it will remove one of the main reasons for giving Labour a bloody nose.

"Effectively he will be saying that you don't need to give me a good kicking because I am going anyway."

But the risk of such a strategy is that if Labour still suffers defeat, it would throw the spotlight on Mr Brown's failings, leaving him to shoulder the blame.

Downing Street strategists have pencilled in Tuesday, May 8, as the favoured date for Mr Blair's announcement.

It is likely to coincide with an upbeat progress report on the Northern Ireland peace process. But the Friday and Saturday after polling day are also possibilities.

The Scottish Opinion survey for The Mail on Sunday shows the SNP is set to become the biggest party in Scotland. But it faces being forced to form a three-party 'rainbow coalition' with the Liberal Democrats and the Greens in order to hold the reins of power at Holyrood.

The poll shows that the Nationalists are poised to capture 44 seats in the 129-member Scottish Parliament. Labour would be on 40, the Liberal Democrats on 18, the Scottish Tories on 13 and the Greens would hit double figures for the first time by winning 11 seats.

With just four more seats than Labour, the SNP would be forced to bring the Liberal Democrats - who had previously shared power with Labour - and the Greens into the Scottish Executive.

The figures come as a bitter blow to Labour, which has been accused of running a 'negative' election campaign attacking solely the SNP.

Last night John Curtice, Professor of Politics at Strathclyde University, said: "The good news for the SNP is that it has a very good chance of beating Labour. The bad news is that it might have to make some deals to form a government. It might end up in office but not in power."

Prof Curtice said that the SNP faced the choice of cosying up to or attacking its potential coalition partners.

"One of SNP leader Alex Salmond's tactical dilemmas in the next 11 days is whether to continue being nice to the Lib-Dems on the grounds that he doesn't want to spoil his chances of doing a deal after the election. Or does he slap them down because otherwise they may pinch too many votes?' he said.

"The Greens are the other party the SNP has to watch out for as they, too, could pick up seats the SNP hopes to win."

The poll showed that 30 per cent of Scottish voters are still undecided and four per cent say they will definitely not vote.