Balancing act
For Alex Salmond, a problem.
His party cannot win the election in the conventional sense of forming the next UK government.
By definition, they only contest seats in Scotland. By dint of simple arithmetic, that means they cannot enter Downing Street as the elected administration.
Solution? Do not fight this election in a conventional fashion. rather than a programme for government.
By which means, the SNP would hope to enter Downing Street to negotiate with the new Prime Minister, whoever that might be.
The SNP would not enter a formal coalition. Firstly, because they rule out that option and, secondly, because nobody else would countenance them as coalition partners.
Rather, they would seek to win concessions on a day by day, issue by issue basis.
"Balanced" parliament
One senior strategist suggested to me that their clout at Westminster might even include an offer to absent themselves at key moments.
For example, say there was a key vote on, primarily, an English issue.
The SNP would usually not vote. But they might threaten to participate, citing Barnett consequentials or whatever. Their absence could thus be won by concessions on another issue.
It is all, of course, predicated on a series of developments. Firstly, a hung parliament.
Mr Salmond - who prefers the phrase "balanced parliament" - says such an eventuality is now "increasingly likely".
Secondly, that the SNP gain sufficient seats, in tandem with Plaid Cymru, to have bargaining clout. The Nationalist aim of 20 Scottish constituencies is notably ambitious.
Thirdly, that other parties agree to play; that they do not exclude the SNP from talks, perhaps because they do not trust them, perhaps because they dislike giving succour to a party which opposes the Union.
Naturally, the SNP's rivals are disdaining the prospect of Alex Salmond or Angus Robertson as kingmakers - or, more accurately, monarchical props.
But the SNP say that this is also a question of arithmetic. The more SNP MPs are elected, the greater the prospect of a hung parliament.
The greater that prospect, the more the SNP can lever out of Westminster.
The SNP was not the only party to launch its manifesto. The , while the , also launched its election drive.
And elsewhere on the campaign trail, Scottish Labour leader Iain Gray , while the Lib Dems' Tavish Scott
The Conservatives Theresa May headed north to
I'm 
Comments
or to comment.