Nicola Sturgeon comes out fighting for full control of Scotland's money, writing exclusively for the Sunday Herald.

One important thing I have learned throughout my political career, via some tough losses and great wins, is that you need to fight the right battles at the right time.

And that is a lesson hard learned for some politicians and some parties - because the brutal reality is that you can devote huge energy, resources and money into a campaign and run up against a brick wall because your message isn't the one people need or want to hear.

So it is with this general election campaign and the efforts of the Westminster establishment parties north of the border - Labour in particular. This week has seen concerted efforts on the part of the old "Project Fear" alliance of Labour, the Tories and Liberals to re-fight last year's independence referendum campaign.

So we have witnessed the twin-track approach of, firstly, trying to conjure up talk of a second independence referendum which, as I made clear this week, simply isn't on the cards at this election, and secondly, trotting out the same anti-independence arguments, but this time in the form of an assault on Scotland having the powers needed to grow our economy and build a fairer society.

Strip away the clunky jargon, and FFA, as some have now shortened it to, simply means Scotland being in charge of decisions on taxation, on welfare policies, on employment and on issues like the minimum wage - powers Labour, the Tories and Lib Dems don't want us to have.

The Westminster parties seem to think it's a great idea to trash this notion of grown-up, responsible financial arrangements for Scotland. But - leaving aside the gigantic effrontery of any Westminster politician lecturing Scotland on fiscal rectitude when the UK's deficit is around £100 billion and its accumulated national debt stands at more than £1.5 trillion - this tactic, underlined by the visit of the two Eds, Miliband and Balls, to Scotland on Friday, entirely misses the point.

People across Scotland know and understand this is not a re-run of the referendum campaign.

So they don't want to hear the phantoms of 2014's fear-mongering. They do want to hear about an alternative approach to the economy and a better, different vision to the dismal Westminster consensus on austerity. They do want to hear about how that different economic approach could impact for the better on schools, hospitals and welfare provision, and our plans for protecting frontline spending on the NHS and education show what is possible. And people do want to hear about how their money can be better spent on giving children a better future, rather than on the grotesque "investment" of £100 billion on a new generation of nuclear weapons.

This election is about giving Scotland a strong voice, and real - perhaps unprecedented - power at Westminster.

In the closing stages of the referendum campaign - which our Unionist opponents seem still to be fighting - we were told, amid the "love-bombing", that Scotland's voice really mattered and that we were a valued part of the UK family. We were told that having a strong voice in Westminster was the best of both worlds - well, now people are choosing to make that voice heard by voting SNP. Getting rid of the Tories - and having a strong voice for Scotland with a group of SNP MPs holding the balance of power - is the best of all worlds at this election.

With just over three weeks to go until polling day, one thing is becoming clearer by the day: Scottish politics is unlikely ever to be the same again after May 7 th.

The current polls are just that - opinion snapshots taken at a moment in time - and, as I have said repeatedly, the SNP takes not a single vote or seat for granted. We know that over the next 25 days we need to work harder than we have ever done before to turn that promising polling into solid electoral reality.

For our opponents, who have made the potentially fatal mistake of choosing the wrong battleground, it may just be the case that they are experiencing one of the toughest of all election experiences - that people have simply stopped listening to them. We will find out in under a month's time.

For our part, we will continue to speak to people across Scotland about our shared priorities - jobs, growth and investment in public services. And a big group of SNP MPs means that at long last we can make Scotland's priorities the priorities at Westminster.