Culture Secretary Tessa Jowell wants the country to ignore "scepticism" around the London 2012 Olympic Games.
Jowell was outlining measures in the London Olympics Bill.
"I am quite sure that in the years ahead we will see...doses of scepticism as the plans for implementing the Games are rightly subject to scrutiny.
"I hope that healthy scepticism will not tip over into unhealthy cynicism because as a nation we have an opportunity we have to seize."
The Olympics Bill sets up the Olympic Delivery Authority (ODA) to ensure that the multi-billion pound investment in venues, athlete accommodation and transport links is delivered on time and within budget.
"The importance of the ODA to the Olympic project is evident: a single body with a clear task accountable to Parliament.
"The Bill we debate today is further evidence of our determination to get moving, to set up the structures to make the Games actually happen and to make sure that the public interest is protected, that public money is properly spent.
"So that the 2012 Olympic and Paralympic Games are delivered on time and on budget.
"Delivering the 2012 Games and the Paralympic Games will be a challenge like no other."