Britain's Tory leader David Cameron urged Gordon Brown to call a snap election saying: "We have got to have real change in our country."
Mr Cameron, speaking as his party's annual conference was about to start in Blackpool, said Labour had failed to deliver on public services and law and order after 10 years in power.
Asked on BBC 1's Andrew Marr show if the Prime Minister needed to seek a mandate after replacing Tony Blair, Mr Cameron replied: "Yes, I think he does."
He added: "I have always said we should have an early election. We are ready for it, we have the candidates ready in our marginal seats.
"We have a very clear and compelling message to people which is that we have got to have real change in our country."
Latest polls showed Mr Cameron and his party both trailing badly behind Mr Brown and Labour but the Tory leader insisted: "This week we will be setting out a very compelling alternative - not just saying what we want to achieve but saying how we want to achieve it.
"They have had 10 years, they have failed and it's time for real change."
But Mr Cameron declined to predict whether Mr Brown would go to the country soon saying: "I may be many things but I'm not a mind reader."
Mr Cameron accepted that the party faced a "huge challenge" in the light of recent opinion poll findings.
But he insisted he was more concerned about giving voters a clear alternative to the Government.