ROBBIE DINWOODIE and DOUGLAS FRASER

The SNP and Scottish Tories face a serious challenge in being prepared for a General Election if Gordon Brown chooses to go to the country sooner rather than later.

The SNP yesterday put its activists on a war footing and ordered constituencies to begin the candidate selection process.

The Conservatives have just two candidates at present - the incumbent MP for Dumfriesshire, Clydesdale and Tweeddale, Shadow Scottish Secretary David Mundell, and the party vice-chairman Richard Cooke in East Renfrewshire.

But the Tories say they always planned to put in place an accelerated selection process after the Holyrood election in May. "We are confident that our candidates will be in place for whenever the election is called," said a spokesman.

An early election would also be a huge challenge for the SNP who poured their efforts into victory in May and are bound to have a shortage of candidates for the next challenge, particularly given that the organisation is now built around Holyrood boundaries which do not apply to a Westminster poll.

Angus Robertson, Moray MP and party business manager, said hopefuls who want to fight for the SNP at the next Westminster election have to move quickly through the vetting process, with plans going before the party's national executive next Thursday which would ensure all candidates are in place by October.

As the SNP is organised according to the 73 Holyrood constituencies, it has to set up separate committees to run the 59 constituency campaigns for Westminster, and Mr Robertson has told party activists not to wait until the political season begins again at the start of September to start that process.

After a disappointing Westminster result in 2005 the party currently has six MPs, and very few other seats now have candidates.

The recent Holyrood election provided a platform to contest several other parts of the country seriously, with Nationalists hoping there is a "Salmond surge" that could compete with the "Brown bounce".

The SNP is targeting not only Labour seats but going after LibDem incumbents where the SNP has MSPs, such as Alan Reid in Argyll, Malcolm Bruce in Gordon and Danny Alexander in Inverness.

The SNP reckoning is that there is up to a 25% chance of Gordon Brown calling a snap autumn election.