As we enter the final stages of the General Election campaign, we are still no closer to being able to accurately predict who will form the next government. With both main parties still struggling to gain any real traction in the polls, it is looking increasingly likely that the vote on May 07 will deliver another hung Parliament.

The current polling projections also suggest that it is more realistic to expect a minority (‘supply and confidence’) government rather than a formal coalition. With the Liberal Democrats fighting to retain more than 25 MPs, and the SNP ruling out any formal deals, the current projections make it very hard for any formal coalition to be formed.

It has been over 30 years since we had a minority government in the UK. There are a number of questions about how this would work in practice, and what concessions parties such as the DUP and SNP would extract for propping up a Labour or Conservative administration.

However, within the current polling projections, there are several viable minority alliances that could be formed (such as Labour-SNP, or Conservatives-Liberal Democrats-DUP) and which would command a majority in the Commons. This would secure a degree of stability for the minority government and their programme of legislation.

A perhaps more interesting question is how much support a minority government would be able to secure in the House of Lords. The current makeup of the Lords is very much dominated by four groups. The Conservatives (227), Labour (216), Crossbench (182) and the Liberal Democrats (103) account for 728 out of the 790 Peers in the Lords. Minority parties, such as UKIP, the SNP and DUP, only have 15 Peers between them. So while a minority party such as the SNP could prop up a Labour administration in the Commons, they would not be able to deliver a majority in the Lords.

This is important, as it would provide any Opposition alliances in the Lords with the ability to seriously obstruct a minority government’s legislative programme. The current Coalition has run into concerted opposition in the Lords on a number of occasions in this Parliament and they have had legislation such as the EU Referendum Bill blocked. Historical precedent provides an even more worrying prospect, as the last Labour minority administration, between 1974 and 1979, lost over 300 legislative votes in a Conservative-dominated Lords.

However, there is a limit to the Lords’ ability to block government legislation. They must follow the Salisbury Doctrine, a Parliamentary convention in place since the 1940s. This convention states that the Lords are unable to block any government Bill based on a direct manifesto pledge.

So, for example, the Lords would not be able to block a minority Labour government Bill on an energy price freeze or a Conservative Bill on an EU referendum. They would however be free to block any legislation based on a new compromise with a minor party. So the Lords would be free to block any Labour-SNP compromise Bill on a Scottish referendum. In this landscape the group of Crossbench Peers will wield far more power than any of the official minority parties.

Whatever the result is on May 07, it looks like the next Parliament will be far more unpredictable and fractious than the current one. Whoever ends up in Downing Street will have to work very hard to build political alliances and secure support across both Houses. But if David Cameron or Ed Miliband are already allowing themselves to speculate on their strategy beyond the election then they would do well to bear in mind their colleagues in the Lords. They might just hold the balance of power over the next five years.