A BLUEPRINT for a new era of progressive politics has been drawn up by a leading Scottish thinktank to help cross-party talks after the election.

Based on the common ground between the SNP, the Greens and Plaid Cymru, the "red lines" campaign is designed to form the basis of a deal with Labour in the event of a hung parliament in May.

The five red lines are: less austerity, a living wage, scrapping Trident, greater devolution across the UK, and replacing the House of Lords.

The plan would form the basis of a so-called "confidence and supply arrangement", in which a progressive alliance of smaller parties would support Labour's budgets and back the government in any votes of no confidence.

Support in each budget in the five-year term would be conditional on the delivery of a new red line.

First Minister Nicola Sturgeon floated the idea of a progressive alliance in December, when the SNP, Greens and Plaid Cymru said they would "unite whenever possible to battle the Westminster parties' obsession with austerity".

SNP Westminster leader Angus Robertson expanded on the idea last week, saying how a large group of SNP MPs could work with "other progressive parties" after May to stop renewal of the Trident nuclear deterrent, and to resist Tory-Ukip demands for the UK to leave the European Union.

The work of the left-wing Common Weal thinktank, the red lines package was drawn up following informal discussions with the smaller parties, but has not yet been agreed by them.

Common Weal is now campaigning for all the parties to sign up to the red lines before May 7.

With polls predicting neither Labour or the Tories will win an outright majority, smaller parties and rebel MPs could wield huge power after May.

Common Weal says the first item on the agenda for a Labour-progressive tie-up should be an emergency budget which uses money earmarked for repaying debt for public services and economic stimulus.

There would also be a crackdown on tax evasion and avoidance, a windfall tax on those who had gained most from austerity, and more state investment.

The red lines for the 2016 budget would be a living wage and repeal of anti-trade union laws.

In 2017, the progressives' demand would be the non-renewal of Trident, with the billions saved used to improve nursery education and childcare.

In 2018, the red line would be devo max in Wales and Scotland, and greater devolution across the regions of England and in local councils.

Finally, the red line for passing the 2019 budget would be a democratic shake-up, with a switch to a proportional voting system for Westminster and the abolition of the House of Lords.

Common Weal Director Robin McAlpine said: "There is some chance this General Election will create conditions in which Britain's flawed democratic system might actually produce an mechanism to force real change. For the first time in its history there is a real possibility that small elected groups not from the large and conservative mainstream parties could become very powerful.

"This campaign is to encourage those groups of MPs to use that power to change Britain forever."

Willie Sullivan of the Electoral Reform Society said: "The old parties, with their roots entwined in the establishment, cannot deliver more equality or democracy, they need to suck up power to one point and that means taking it away from others. "The small parties could be part of a broad movement, sharing power bestowed by the electorate, not big donors or media barons."

Peter McColl, Green candidate in Edinburgh East and Rector of Edinburgh University, said: "There's a real demand for a politics that sees public services as an investment, that sees spending money on children as more important than spending money on nuclear weapons and that understands the need for real reform to Westminster."

Scottish Labour declined to comment.