David cameron has told The TES that cuts will have to be made to the Department for Children, Schools and Families (DCSF) if the Conservatives win the general election.
The Conservative leader described the country as being in a "desperate situation" and said "savings" would have to be made whoever formed the next government.
Mr Cameron also said he would be putting education "front and centre" during his campaign to become the first Conservative prime minister for 13 years.
Education would be "absolutely crucial" to his party's battle plan, he said, adding that any government he leads should be judged by how well it performs on education.
But it is the government coffers that the Conservatives will have to turn their attention to first if they come to power in May.
"The Government has borrowed and spent like it's going out of fashion and we now have debts that we have to start paying back - there are no ifs and buts," Mr Cameron said.
"So I'm not going to soft-soap you here. There is no question that whoever forms the next government will have to find savings in the DCSF budget. Any suggestion otherwise would be dishonest.
"But if there is something I hear from teachers all the time, it's that there is so much waste already. In fact, less than two-thirds of the DCSF budget goes directly to schools. So I completely reject the idea that we can't find savings without harming schools."
The Conservative leader said his party would start making savings by abolishing quangos such as the Qualifications and Curriculum Development Agency and cutting back on government initiatives.
Mr Cameron described how he had asked his then leader Michael Howard to be handed the shadow education role in 2005, and has made education one of his key areas for reform since becoming leader alongside welfare and strengthening families.
Under the Labour Government, schools had become "overly prescriptive" and teachers' enthusiasm for their jobs was running the risk of being "crushed", Mr Cameron added.
He said he wanted to bring "more power and control" back into the lives of teachers.
"This Government has made teachers' lives more difficult, questioning their judgment through more rules and regulations and sending them into some chaotic environments with no proper protection," he said. "We want to change all that . So we will scrap all the National Strategies and end the stream of government advisers who come in and tell you how to do your job."
However, Ed Balls, Schools Secretary, said: "David Cameron is concealing from teachers and parents the fact that he has consistently refused to match Labour's pledge of rising spending per pupil over the next three years. So when David Cameron talks about savings he hides the truth that the Tories would make deep cuts to all our state schools.
"We are already making cuts to central programmes and our agencies in order to protect funding for the frontline and are helping schools to make every penny go farther, but the Tories have to find billions of pounds of cuts on top of that, which every school knows could only come at the expense of thousands of teachers and teaching assistants.
"As for his talk about freeing up teachers, David Cameron should explain why he wants to prescribe from the centre exactly what should be taught in history and why last week the Tories sabotaged the new primary curriculum, which would have given teachers the freedom and flexibility they have been calling for."
Original paper headline: `No ifs or buts': Cameron says cuts must be made in the DCSF