SNP leader Alex Salmond has said success for his party at the General Election would "make Westminster dance to a Scottish tune".
The minority SNP administration in Edinburgh has put forward plans for a referendum on Scottish independence despite opposition from Labour, the Tories and the Liberal Democrats.
The nationalists have set themselves the target of winning 20 seats at Westminster at this election - about three times its current tally of seven MPs - to form a "Scottish bloc" of MPs who could potentially hold the balance of power in a hung parliament.
Referring to Robert the Bruce's declaration of Scottish indepence in 1320, Mr Salmond said: "This is a great day to call an election. April 6 is the anniversary of the declaration of Arbroath, Scotland's declaration of independence.
"I doubt very much if Gordon Brown realised that when he chose today to call the election, but it must be an auspicious sign for Scotland and for the SNP."
He added: "Our target is 20 (Westminster seats). It's an ambitious target. That would be a huge Scottish bloc, and in conjunction with our Welsh allies in Plaid Cymru, we could make Westminster dance to a Scottish tune."
