Lord Coe believes the final 50 days of campaigning will make or break London's bid to host the 2012 Olympics.
London has unveiled a new image to mark the 50-day countdown
Coe is confident London can beat Paris, New York, Madrid and Moscow in the final vote in Singapore on 6 July.
"We will carry on getting the message out right until there is no more time to get the message out," said Coe.
"Nobody really knows what the pecking order is and if anyone tells you what's going on they are either hoodwinking you or they are making a guess."
London 2012 ambassadors Jonathan Edwards, Nell McAndrew and Jo Fenn marked the 50-day countdown by unveiling a series of billboards in central London on Tuesday.
The adverts, backed by 10 national newspapers and featuring some of London's famous landmarks, will be sent around the city to promote the bid.
New laws to help manage the Games if London wins were also announced.
The battle for 2012 is now reaching the closing stages, with the International Olympic Committee's inspection team due to publish its evaluation report on the rivals on 6 June.
There will then be an opportunity to appeal to African IOC members at a gathering of national Olympic committees in Accra, Ghana.
And the cities will have a final chance to impress in presentations just before the final vote of IOC members in Singapore.
Paris is widely considered to be favourite to win the IOC vote, with London believed to have narrowed the gap and Madrid also reported to have gained ground in recent months.
"I think we are in with a very good shout," Coe told BBC Five Live before the Laureus World Sports Awards in Estoril.
"I've never for one minute doubted that. Over the last year we've made unbelievable progress.
"We didn't come out of the initial evaluation phase in January 2004 in bad shape, but we didn't come out in great shape.
"We had to address some very big issues very quickly.
"We had to talk properly about our transport plan, and we had to make sure that the IOC knew government from the very highest level was on board and that in deliverability we can do this.
"All those things I think we have done extremely well, and I think the evaluation team when they came through the city in February were very impressed.
"We will wait until 6 June for their executive summary of what they found. I think we will come out of that pretty well, but I don't prejudge that."