Formal negotiations between Labour and the Liberal Democrats have resumed in the House of Commons, as the parties struggle to form a viable government five days after the General Election.

Conservative leader David Cameron insisted this morning that it was "decision time" for the Liberal Democrats, after his party offered an enhanced deal including a referendum on scrapping the first-past-the-post system for Westminster elections.

Schools Secretary Ed Balls has said Labour must protect its manifesto and needs time to strike the right deal with the Liberal Democrats.

He told reporters on his doorstep: "We need to take the time to get it right and I am very clear my job is to be there with the whole negotiating team to make sure we protect our manifesto, but also the country needs a stable government."

Meanwhile, potential successors to Gordon Brown - who announced on Monday his intention to step down - this morning dodged questions about whether they would be candidates in the race to be Labour leader.

Emerging from his house in south west London, Mr Clegg said he was "as impatient as anyone else to get on with this, to resolve matters one way or another".

In a brief statement, he told waiting reporters: "My parliamentary party was up into the small hours yet again discussing things. We will act, as ever, responsibly. We will act to try to do our bit to create a stable, good government that the British people deserve.

"And I really hope that we will be able to make an announcement so we clear up everything and explain to people exactly what our thinking is as quickly as we possibly can."