Gavin Williamson will have to deliver an increase in spending on England's schools after replacing Damian Hinds as the new education secretary.
Mr Williamson was sacked from his previous post as defence secretary at the start of May after an inquiry into a National Security Council leak.
Boris Johnson pledged to increase school budgets on his first day in office as the new prime minister. Head teachers said tackling the "funding crisis" should be a priority.
Mr Hinds was commended by the ASCL head teachers' union for his efforts to tackle recruitment and retention problems for teaching. But the incoming education secretary, who was taught at a comprehensive in Yorkshire and then studied at the University of Bradford, faces the unresolved challenge of school funding shortages.
"The government has ducked this issue for far too long and its negligence in this regard has brought the education system to its knees," says ASCL union leader Geoff Barton.
Jules White, the head teacher who has organised the WorthLess? school funding campaign, said the new education secretary should "ditch the 'more money than ever' nonsense" and deliver the extra money needed by schools. But there are likely to be differences over how much funding is needed.