David Cameron has targeted "coasting schools" - defined as those that while not failing, are giving children a "mediocre" education.
In a keynote speech today, the prime minister predicted the change would be "incredibly difficult to push through" but added he saw it as "a fundamental test" of his new majority Conservative government.
"Coasting schools are those where standards have been mediocre for too many years and aren’t improving quickly enough. Schools where standards could and should be higher, given their in-take and potential," he said.
"These include some schools rated ‘Requires Improvement’ – but who aren’t improving quickly enough. And other schools rated ‘Good’ at their last inspection – but which haven’t been maintaining high standards since. They are giving children 'just enough' to avoid falling beneath our floor standards. But frankly ‘just enough’ isn’t good enough for my children, and it shouldn’t be for yours.
Cameron, speaking in a school in Runcorn, Cheshire, said: "So we’re going to say to those schools: if you’re not making fast enough progress in raising standards, you have to change and if you can’t do it yourself, you have to become a sponsored Academy and welcome in people with a proven track record of running outstanding schools.
"Taken together, these changes mean we will turn around 1,000 more failing schools .and improve hundreds more coasting schools.
Education secretary Nicky Morgan will set out in parliament today what principles the government will apply to judge whether schools are "coasting".