Nick Clegg has insisted the coalition was already proving doubters wrong as he took temporary charge of the reigns in Downing Street.
The Deputy Prime Minister said the Government was proving to be "radical and reforming" rather than the "insipid mush" many had predicted.
Speaking at a Town Hall-style event hosted by MSN.com in London, Mr Clegg was asked how he thought the coalition had performed in its first 100 days in power.
"I think many people felt that a coalition government by definition would be some sort of insipid mush, where different parties sort of haggle constantly with each other until they produce some lowest common denominator policies that do not really make a difference," he said.
"Actually, what we are finding out after after 100 days we are being accused of doing exactly the reverse, which is doing things too quickly, too fast, too radical, too reforming.
"I think that is a sign of a government - whether you agree with it or not - that has got a strong sense of purpose."
Asked if he imagined a few months ago that he would be taking the helm of government, the Liberal Democrat leader replied bluntly: "No."
He stressed that Prime Minister David Cameron was still officially running the country despite being on holiday.
"I'm holding the fort for a couple of weeks and I'm doing so in the spirit of partnership," Mr Clegg added.