Gavin Williamson proved himself to be an "A* individual and an A* secretary of state" during the A-level exams fiasco, his Cabinet colleague Jacob Rees-Mogg has claimed.
The leader of the House of Commons defended the education secretary after Labour took aim at him, saying he had done an "absolutely first class job under difficult circumstances".
Mr Williamson has repeatedly apologised to students after an algorithm unfairly downgraded hundreds of thousands of results before a U-turn was performed allowing pupils to use the scores their teachers had predicted for them.
But he has also repeatedly refused to resign over the debacle which saw him stand by the results for several days before he was forced to back down amid pressure from students, headteachers and MPs.
Mr Rees-Mogg claimed Mr Williamson's decision to shift policy showed he is "able to react to a situation quickly and put it right", despite it taking him four days to change his mind.
"The real success of governments is when there is a problem being able to put it right and that is what (Mr Williamson) did and for which he deserves the most enormous credit."
Shadow Commons leader Valerie Vaz said: "On Tuesday, (Mr Williamson) didn't apologise for the debacle.
"All he said was he was deeply sorry that those who have borne the brunt have been students, nothing about the mistake, no mention that students had to demonstrate to be heard."
Exams regulator Ofqual has suggested Mr Williamson should accept his share of the blame for the exams fiasco.
The chair of Ofqual, Roger Taylor, told the Education Committee on Wednesday that the regulator accepts responsibility for creating the doomed algorithm but said the decision to use a standardisation formula "was taken by the secretary of state".
He said Ofqual knew about concerns that some students would have their scores downgraded, but insisted Mr Williamson was "fully informed".
He rejected any suggestion that the education secretary was not aware of issues with the standardisation formula, but said Ofqual accepted responsibility.
"We kept the Department for Education fully informed about the work we were doing and the approach we intended to take to qualifications, the risks and impact on results as they emerged.
"However, we are ultimately responsible for the decisions that fall to us as the regulator."