Next week, the Prime Minister will come north of the border to deliver a keynote speech when he will set out his personal passion for maintaining the United Kingdom family with a 'Scotland we love you, stay with us' message.
No 10 hinted that there would be more ministerial visits in the final days of campaigning but sources stressed that, despite the Yes campaign boasting the momentum is with the pro- independence argument, people should not expect a new approach or change of strategy from the UK Government as passions rise towards referendum day.
Speaking from the Nato summit in Wales, Mr Cameron, who has said he is a Unionist "head, heart and soul", strongly denied the Nationalists' repeated charge that the No campaign had been grindingly negative
"I don't think it's been negative or complacent," said the PM. "The No campaign is working very hard to make an important set of arguments. Certainly, my role in the campaign has been to make a wholly positive case, very much saying to people in Scotland - look, it is your choice but the rest of the UK - England, Wales and Northern Ireland - we want you to stay.
"My argument throughout, and a large part of the No campaign's argument, is not saying - look, Scotland can't be independent; of course, it could be independent but we would all be better off by staying together."
Asked if he would put more heart into the campaign and would say 'Scotland we love you, stay with us', he replied: "I have absolutely said that in terms and will say so on my next campaign visit."
The Conservative leader - regarded as "toxic" to the campaign by many in the No camp - argued that being a proud Scot and a proud Brit were not mutually exclusive.
"I would argue you can be far prouder of your Scottishness, your Scottish identity, your belief in Scottish history and traditions and still believe you can succeed in the UK. It's not true that the only patriotic option is to vote Yes; you can be a proud patriotic Scot but believe in this family of nations we have in the United Kingdom."
Asked if he would resign if there was a Yes vote, showing he had failed to keep alive the 300-year-old Union, he replied: "It's important to say no to that emphatically for this reason; what is at stake here is not this prime minister or that prime minister or this party leader or that party leader, what is at stake is the future of Scotland. It is for the Scottish people to decide - do you want to separate yourself from the UK or do you want to stay in the UK?"
When it was pointed out that the people of the rest of the UK might feel hard done by if he failed to keep the country together, he said: "It's important for people in Scotland to realise the consequence of their vote is purely and simply about Scotland and its place in the UK. We shouldn't tie up into this vote the future of Alex Salmond, the future of me or anyone else."
He added: "This is about the future of Scotland. It's a desperately important question. I care passionately about it. It would break my heart if Scotland were to leave the UK but I absolutely believe it's right to give people in Scotland the choice. I dearly hope the Scottish people will vote to stay in our family of nations."
l Scottish Conservative leader Ruth Davidson has insisted she is "confident but not in the least complacent" of a win for No in the independence referendum, as she faced concerns from Better Together supporters.
The Tory leader said the No campaign was working flat out to secure victory, stating it was the responsibility of everyone to ensure people go to the polls to make their voices heard.
Ms Davidson faced several questions from her own supporters about the effectiveness of Better Together's campaign at an event in Perth.
Audience members expressed concerns that the movement could be failing to get the "message of the heart" across to the electorate.