David Cameron has admitted he "contemplated having to go" if Scotland voted for independence.
The Prime Minister said he would have been "heartbroken" by the break-up of the UK and considered his position when polls put the Yes campaign ahead just days before the referendum.
A former candidate for the leadership of the SNP has ruled out standing for the position again in the wake of Alex Salmond's sudden resignation.
After Scots voted against independence, Mr Salmond announced he will be stepping down from the position of both SNP leader and First Minister.
Roseanna Cunningham stood for the leadership of the party against Mr Salmond in 2004.
A spokesman for Ms Cunningham, the community safety minister in the Scottish Government, said: "Roseanna wants to make it quite clear that she has absolutely no intention or desire to stand for either the leadership or the deputy leadership of the party.
Deputy First Minister Nicola Sturgeon has already emerged as the clear favourite to take over from Mr Salmond, when he formally steps down at the SNP annual conference in November.
The woman expected to replace Salmond said she will "follow the mood of the people" if promises made in the run up to the vote are not met.
The double Grand Slam winner said he did not regret giving his opinion, but was 'disappointed' at the way he went about it.
Alex Salmond has announced his intention to end a 24-year career at the forefront of Scottish politics. Here is a brief look at his career.