TENSIONS between the main No parties are bubbling to the surface after a wobbly few days for Better Together.

Labour voices believe George Osborne and Alistair Carmichael made a hash of Sunday's announcement that a timetable for agreeing and delivering greater devolution was imminent. The Chancellor's comments created an expectation that new powers would be offered, but no such plan is on the table.

The Conservatives, meanwhile, especially Westminster backbenchers who are finally waking up to the referendum, are aghast that Labour seems to be struggling to persuade its own supporters to vote  No. They point to polls showing Ed Miliband, who is due to campaign alongside Gordon Brown at a rally later this week, is no more trusted in Scotland than David Cameron.

Better Together is not yet panicking but there is concern over the tightening polls, which do not reflect Labour's own canvassing. Party insiders insist their contacts with tens of thousands of voters, not just their own supporters, reveal consistently high levels of support for a No vote.

Their bafflement will not be aided by today's TNS poll, the third in a row after recent Panelbase and YouGov surveys saying the referendum is balanced on a knife edge. However they do believe the numbers "will focus minds and spur people to action," as one insider put it.

Better Together is also taking comfort from Quebec's 1995 referendum. The Yes side was seven percentage points ahead at a similar stage but lost (albeit by a whisker). The lesson of most referendums, say Better Together strategists, is that the side calling for change needs a substantial lead going into the vote, as caution takes over in the privacy of the polling booth.

They also believe the slide in the value of the pound, down by one per cent at one point yesterday, the biggest single-day dip for more than a year, will alert people to potential economic risks of independence.

The Yes campaign, however, also sees an opportunity in the pound's fall. Some Nationalists believe Mr Osborne will have to give his public backing to the SNP's currency union proposal in order to calm market jitters. It's hard to see that happening. A U-turn on that scale would surely dent the Chancellor's credibility beyond repair. However, Nicola Sturgeon attempted to turn the tables on the Chancellor yesterday, saying currency union talks now would give the markets some reassurances. "It is the UK Government that's creating the uncertainty by refusing to have those sensible discussions," she said.

The Yes campaign has handled its surge in the polls with great care. Privately, senior SNP figures have said they would rather not have taken the lead at this stage (YouGov put Yes ahead by 51 per cent to 49 per cent, excluding the don't-knows, on Sunday) fearing it would produce a bounce back to No. As a result, Alex Salmond and Ms Sturgeon have been at pains to stress the Yes camp remains the underdog.

Meanwhile their foot soldiers are enthused, energised and armed with a strong sense of belief that victory is within their grasp in nine days' time. What's not in doubt is how crucially important these final days have become to both sides.