The Scottish National Party pledged Saturday to "shake up" the British parliament if they seize the balance of power at the general election in May.
SNP leader Nicola Sturgeon said her pro-independence party would act in the interests of left-wingers across the United Kingdom if they are in a position of influence after the May 7 polls.
Scotland`s first minister used her speech to reach out to people in the rest of the United Kingdom with a "message of friendship and solidarity".
"I won`t pretend that the SNP doesn`t still want Scotland to be independent," she told a party conference in Glasgow, in reference to the September referendum vote to remain part of the three-centuries-old union with England.
"But... I say this to people of progressive opinion all across the UK.
"As long as Scotland remains part of the Westminster system, we will be your allies in seeking to shake up and reform that outdated and discredited system once and for all."
Sturgeon said SNP lawmakers would "demand an alternative to slash and burn austerity" -- referring to the public spending reductions being made in a bid to balance the budget.
She said the nationalists would stand against any attempt to renew Britain`s nuclear weapons deterrent, and added it was time to abolish parliament`s unelected House of Lords upper revising chamber.
At the last general election in 2010, the Labour main opposition won 41 of Scotland`s 59 seats in the British parliament`s 650-member lower House of Commons, to the SNP`s six.
But following a surge in support, the nationalists are tipped to win at least 40 seats this time around, making it difficult for centre-left Labour to form a majority government.
The SNP have proposed backing a Labour minority government on a vote-by-vote basis, with Prime Minister David Cameron`s centre-right Conservatives claiming that would mean the separatists perpetually holding Labour to ransom.
"If you want a Labour government to have backbone and guts, you need to elect SNP MPs to provide it for them," Sturgeon said.
"You must elect SNP MPs to force Labour`s hand and keep them honest."
Scottish Labour leader Jim Murphy said: "No-one will be fooled by Nicola Sturgeon`s claims to be the UK`s best friend when the SNP`s entire purpose is trying to break up Britain."
Labour former prime minister Gordon Brown, who is standing down from parliament, said Sturgeon was offering "the right hand of friendship to keep the left hand free to deliver the knockout blow to break Britain apart".
"The surest way to get a Labour government is by voting Labour, and not voting for someone else," he added.