Nicola Sturgeon will today pledge that her party will work with others to bring about "positive change" for ordinary people across the UK.Read the full story ›
The Scottish National Party would block any Conservative minority government by voting down the Queen's Speech if the Tories win the largest number of seats but fall short of a majority.
As leaders prepare for the final Prime Minister's Questions before Parliament dissolves ahead of the general election in May, former SNP first minister Alex Salmond had said his party would do their utmost to clear the way for a Labour-led government.
In an interview with New Statesman, Mr Salmond did not rule out a formal coalition with Ed Miliband, despite the Labour leader explicitly rejecting the idea.
He said the SNP could enter a "confidence and supply" arrangement with Labour by agreeing not to bring down a minority government in return for concessions on certain issues, and would try to influence any budget.
The Tories would have to go straight effectively for a vote of confidence - usually the Queen's Speech, although it could be otherwise, of course, and we'd be voting against.
So if Labour joins us in that pledge, then that's Cameron locked out. And then under the (Fixed-Term) Parliaments Act that the Westminster parliament's passed but nobody seems to have read, you'd then have a two-week period to form another government - and of course you want to form another government because this might be people's only chance to form another government.
Nicola Sturgeon has told Good Morning Britain that the Liberal Democrats are facing "political annihilation" because they "abandoned their principles" during five years of coalition.
The SNP leader said Nick Clegg's party had shown "how not to do it" as a smaller party in coalition.
"The Liberals have in my view got themselves into the position they are in now - facing political annihilation in a few weeks time - not because they went into coalition, but because they went into coalition and immediately abandoned all their principles," Sturgeon told GMB's Susanna Reid.
Asked how many seats her party was targeting on May 7, Sturgeon said: "I'm not going to put a number on it; opinion polls don't win election - hard work, persuasion, having the best policies and best ideas for the country win elections."
Last week, Sturgeon told ITV News that her party could work together with Labour as part of a "looser arrangement" to keep the Tories out of Downing Street in the event of a hung parliament.
There will be no SNP ministers under a Labour government, Ed Miliband insisted today.
Yet SNP leader Nicola Sturgeon said that, while a coalition was unlikely, Labour and the SNP should work together to "lock the Tories out" of Westminster.
But polls suggest that it may be inevitable that either Labour or Conservatives will have to join forces with another party to form a coalition.
ITV News Political Editor Tom Bradby reports:
Nicola Sturgeon has said the SNP and Labour can still work together as part of a "looser arrangement to keep the Tories out of government" in the event of a hung parliament after May's election.
Speaking after Labour leader Ed Miliband ruled out a formal coalition with the SNP, Sturgeon told ITV News' Chris Ship: "It doesn't stop us working together in a looser arrangement to keep the Tories out of government.
"As long as there are more anti-Tory MPs in the House of Commons than Tory MPs, we can lock David Cameron out of Downing Street."
Ed Miliband decided to clarify Labour's position on an SNP coaltion in the face of a "protracted and concerted campaign of misinformation" by the Tories, a senior Labour source said.
The Conservatives had "given up on the people of Scotland" and were not making a positive effort to win the election outright, the source added.
Following Ed Miliband ruling out a coalition with the SNP in the event of a hung Parliament in May, Nicola Sturgeon posted a Twitter message to clarify that no one had actually proposed the union.
The SNP leader and Scotland's First Minister added that any relationship between the two parties would be in a bid to "lock out" the Conservative Party.
Miliband rules out a formal coalition no one was proposing! Fact remains if more anti Tory than Tory MPs in HoC, we can lock Tories out.
Labour leader Ed Miliband has ruled out a coalition with the Scottish National Party and said there would be "no SNP ministers" in any government he leads.
Speaking to an audience at People's Question Time in Guiseley, West Yorkshire, he described the idea as "nonsense".
He accused the Conservative Party of running a misleading campaign based around the idea of a Labour SNP union.
As I said on Thursday night, this idea is nonsense, it will not happen. There are big differences between us on a whole range of issues.
Not just on the integrity of the United Kingdom and another referendum but on fair funding between the countries of the UK and on fair taxes.
...Labour will not go into coalition government with the SNP. There will be no SNP ministers in any government I lead.
Shadow chancellor Ed Balls has said that it is "nonsense" to suggest a Labour post election deal with the SNP.
"We don't want a deal with the SNP. Its not part of our plans, It's nonsense," he said on the Andrew Marr show.
"I think it is the Tories and Ukip who are doing a deal. Its's probably happening around Micheal Gove's kitchen table."
David Cameron has called on Ed Miliband to rule out any post-election pact with the SNP, saying a party which wants to "break up Britain" has no place in the country's government.
The Prime Minister said a Labour administration supported by the SNP's votes would be the "worst outcome" for the UK.
If you thought the worst outcome in this election is a Labour government led by Ed Miliband, think again.
You could end up with a Labour government led by Ed Miliband, propped up by Alex Salmond and the Scottish National Party.
You could end up with an alliance between the people who want to bankrupt Britain and the people who want to break up Britain.
Even today, Ed Miliband will not rule out a deal or backing from the SNP.
If he cares about this country, he should do so. You cannot let the people who want to break up our country into the government of our country.