Iain Duncan Smith has told his party not to underestimate him and to stop dwelling on past glories.
In his speech at the Tories' conference in Bournemouth, he said the party must embrace his decision to make modernisation of public services the top priority.
The leader has challenged the party to recognise that the political agenda has moved on from the Thatcherite economic revolution.
He says the focus is now on quality of life issues like crime, education and health.
Mr Duncan Smith has sought to stamp his authority on the party by telling activists: "Do not underestimate the determination of a quiet man."
He has argued the party has to stop living in the past and has warned its reactionary element will be left behind. The leader also emphasised his determination to see his reform programme through to its end.
He told members: "Those who do not know me yet will come to understand this: When I say a thing, I mean it. When I set myself a task, I do it. When I settle on a course, I stick to it.
"Do not underestimate the determination of a quiet man," he added.
Mr Duncan Smith also insisted the conference, which featured 25 policy announcements, represented a watershed for the party.
"This will be remembered as the week when the Conservatives began the slow, hard road back to power," he argued.