Sturgeon: Westminster parties have hit the panic button

With her SNP tipped to take as many as 50 seats in the election, Ms Sturgeon could end up holding the balance of power - with the Conservatives raising concerns about the impact this could have on the rest of the UK.

But Ms Sturgeon, speaking out ahead of a campaign visit to Kilmarnock, said that in this "people's election" there is widespread public support for a different approach.

The First Minister and SNP leader said: "As we enter the final ten days of the election campaign, it is clear that the Westminster parties have hit the panic button.

"Instead of embracing the multi-party election that the public want, Labour and the Tories are clinging to the idea that they are entitled to a majority in Westminster - which every poll indicates isn't going to happen.

"The reality is that this is the people's election, and voters do not appear to trust either party with a majority. The SNP is being open and honest about our position, that we will work to keep the Tories out and to keep Labour honest."

She warned Ed Miliband, who yesterday appeared to rule out any form of post-election deal with the Scottish nationalists, that "Labour would never be forgiven if they let the Tories back in in preference to working with the SNP".

Ms Sturgeon said: "The support and enthusiasm from voters in all parts of the UK for the different approach to politics and the end to austerity that the SNP is putting forward shows the growing distrust of the Tories, Lib Dems and Labour.

"And while others are campaigning on fear and division, we are setting out policies that support the NHS - across the whole of the UK, that would help those in poverty wherever they live, support women and young people, and that back business in all parts of the UK.

"The SNP is campaigning to win the support of the people of Scotland in order to make Scotland stronger at Westminster, to end the cuts, to invest in jobs, and to protect our vital public services.

"Those Westminster politicians who have chosen to engage in the politics of negativity, and who are seeking to deny Scottish MPs their democratic rights in the House of Commons, are doing the public across the UK a deep disservice."

Len McCluskey, general secretary of the Unite union, which is Labour's biggest donor, said he expected Mr Miliband to work with "any progressive party" if he becomes prime minister.

Speaking during a campaign visit to Scotland, Mr McCluskey told the Guardian: "I'm expecting Ed Miliband to be prime minister and, in those circumstances, I would expect him to work well with any progressive party who seeks to support the vision that he has of changing Britain for the better."

Mr McCluskey said his union's membership in Scotland was "pretty well split" between support for Labour and the SNP, adding: "It would be wrong of me to launch an attack against the SNP, who have a manifesto that is anti-austerity, which is Unite's policy, and many of the issues that they talk about are in line with the policies of my membership."

The SNP had "undoubtedly changed the contours of the political scene and we have to respond to that, in particular the trade unions", said Mr McCluskey, adding: "It's a trust issue. Whether we like it or not, the SNP appears to have gained some trust of the Scottish working class."

In an interview with the BBC Radio 4 Today programme, Ms Sturgeon said she would not bring down a Labour government and allow the Tories into power but said day-to-day Commons votes did offer the chance for a large SNP block to wield "enormous clout".

She said: "Exercising influence in a Parliament is not just about the Queen's Speech. It's about how you exercise influence on an issue-by-issue, vote-by-vote basis throughout the entirety of a Parliament.

"This is important expertise the SNP could bring to bear, we have been a minority government. We know how it works, we know how to get things done and we also know the way in which compromises have to be struck - Ed Miliband can say what he wants right now, he's entitled to do so, but he can't deny reality.

"If there is a situation after the election where neither of the big parties has a majority then they will have to reflect how people have voted and they will have to on a practical level be prepared to talk to others and compromise with others in order to get their policies through.

"Whether that is part of a formal deal or on an issue-by-issue basis, it gives parties like the SNP enormous clout and enormous influence."

She added: "Under the Fixed Term Parliaments Act it is possible for other parties to change the direction of a government without bringing a government down. That gives enormous influence."

The SNP leader rejected the suggestion that her party was more austere than the Labour, insisting "every single penny" had been passed on from grants to the health service.

Ms Sturgeon said: "We are putting forward as part of our anti-austerity argument the fact we would vote for considerable increases in health spending across the UK to meet the terms of the Stevens Report and ensure as we go into the next decade the health service is properly equipped to face up to the challenges it will meet."

She added: "As long as Westminster decisions affect Scotland it matters to the SNP and it matters to Scotland that those decisions are good decisions, to we have a vested interest in making sure the politics at Westminster is better politics."