The nationalists are barely more left-wing to begin with.
The party is forecast to spend less than Labour and the Lib Dems by the end of the parliament through slower but longer austerity.
There is a Commons majority for Trident and the party couldn't amend Budgets in the way it hopes.
Shadow chancellor says Leader of the House would "talk to all parties" but rejects negotiations on the Budget and defence.
The PM suggested that a Labour government reliant on nationalist support would be forced to cancel infrastructure projects outside of Scotland.
After the nationalists' pledge to oppose the Tories, Miliband could simply invite them to support a left-wing Queen's Speech.
Miliband again impressed - but the limits of the format left him unable to land the knock-out blow against the PM he craved.
The SNP's stance and the Tories' missteps mean Miliband is in the strongest position to become prime minister.
Tories are pushing the Prime Minister to consider how he could work with Salmond's party in a hung parliament.
Rejecting any arrangement with the SNP would make it far harder for the Labour leader to become prime minister in a hung parliament.
As a new study by the Resolution Foundation shows, the difference between the two parties could be "relatively modest".