Ed Balls has launched a robust defence of the controversial National Challenge and said he would not have changed any aspect of the way it was introduced.
The Schools Secretary's comments follow sustained criticism of the Government's handling of the scheme.
At the launch of the initiative last summer, schools where fewer than 30 per cent of pupils achieved five good GCSEs including English and maths were threatened with closure. As the programme continues, many remain angry that their results with children from disadvantaged backgrounds are not being recognised.
But Mr Balls, speaking at the North of England Education Conference last week, said: "When we launched the National Challenge, it was very clear and very challenging and controversial. I don't regret any aspect of what we did."
He said it was necessary to endure negative headlines about the initiative in order to "wake people up to the scale of your ambition".
"We were saying that every school could rise up to 30 per cent with English and maths and beyond, and that we were going to be uncompromising in our commitment to making it happen," he said.
The publication this week of GCSE results for individual schools showed a substantial drop in the number under the 30 per cent threshold, falling from 638 to 440.
But Mr Balls insisted that more than 200 secondaries from the original list were letting pupils down and needed fundamental change.
"I can't believe that there is any good headteacher who would ever be satisfied with 30 per cent of their kids getting five GCSEs with English and maths, and 70 per cent not," he said.
Mr Balls also criticised school governors for failing to take enough action in schools with persistently low results.
"There are also some schools where the leadership team has not been strong, where the school has been stuck below 20 per cent for a few years, and where actually you have to question whether the governors have been sufficiently challenging the school and the leadership team," he said.
Too often governors do not get the training and support needed to do their jobs properly, he added.
Elsewhere at the conference, delegates raised concerns that the National Challenge scheme was hindering the work of other school improvement programmes.
Mel Ainscow, chief adviser to the Greater Manchester Challenge, which offers schools help to improve, said a number of heads were still "sore" about their treatment when the scheme was launched. But he added that others had "moved on" now that they were getting extra support in their schools.
One head involved in the Manchester scheme, which was modelled on the popular London Challenge, told The TES that schools had become cynical about what it would offer them.
He said: "We had been told about collaborative working and transformation, and in came the National Challenge. And we thought, 'Yeah, that's what it's really about.' We are still having to tackle that obstacle."
Pounds 400M TO IMPROVE
The National Challenge was launched last summer to ensure all schools meet minimum exam targets.
Schools where fewer than 30 per cent of children achieve five good GCSEs including English and maths were told that they risked closure if they did not improve.
The initiative came with a promise of Pounds 400 million of extra funding to help the 638 schools.
Ministers said half the money would pay for 70 of the schools to be converted into academies, and 120 others would be converted into trust schools, giving them control over budgets and staffing. Teachers' leaders criticised the move for its focus on raw results instead of contextual value added scores.
The scheme is based on the London Challenge, which was launched in 2002 to offer extra support to low-attaining secondaries in the capital. The London scheme has been praised by schools and has seen results improve considerably.