First Minister Alex Salmond calls it panic.

At best, it could be called last-minute. Whatever the right description, tomorrow the three Westminster parties will unveil their plans to offer Scotland more powers on tax, spending and welfare if Scots vote against independence. There will also be a timetable and a structure for implementation of the plan.

In a speech in Midlothian last night, former Prime Minister Gordon Brown began to lay out a roadmap for the plan. A No vote, he suggested, would be the starting gun for delivering enhanced devolution to a strict timetable. He proposes intensive consultation with civic Scotland and agreement on new legislation by the end of November, just five weeks after the referendum. It would be, said Mr Brown, nothing less than a modern form of Scottish Home Rule within the United Kingdom.

The speech amounts to a robust intervention in the campaign with just nine days to go and we will know tomorrow whether agreement has been reached around such a plan. What would be disastrous for Better Together at this stage would be any equivocation.

If they agree a plan, the Westminster leaders hope it will secure a No vote after a number of polls in recent days showing the fight is neck and neck. But if the offer fails to work, and there is a Yes vote, both Prime Minister David Cameron and Labour leader Ed Miliband will be in serious trouble - trouble to which they are only now perhaps waking up.

Arguably, the trouble is most serious for Mr Cameron. This week, he will be offering greater devolution but it was he who vetoed a question on the ballot paper that would have offered the very same thing. The theory was that, with a choice between the status quo and the uncertainty of independence, Scots would pull back from the brink, but that theory looks like it be might be unravelling. In the wake of a Yes vote, the lack of a third question will look like a disastrous miscalculation.

However, Mr Miliband should take no comfort from this because the consequences of a Yes vote are just as serious for him. On his visits to Scotland, he has argued he can win next year's General Election and he will use the victory to build a fairer Scotland in the UK, but the evidence would appear to suggest the argument is failing to convince the Labour vote in Scotland.

In his speech, Mr Brown tried to appeal to those voters when he said Labour was the party of home rule, but the polls suggest much of the movement towards Yes is coming from voters who supported Labour in 2011. That they are failing to support Labour's position in the referendum will be blamed on Mr Miliband and his Labour colleagues who have largely led the No campaign, but arguably fought it like any other General Election.

Panic or not, the response is for the Westminster parties to lay out their plans tomorrow. If it works, it may save the Union and lead to a very different UK; if it fails, it will lead to an independent Scotland and may cost Mr Miliband and Mr Cameron their jobs.