The head of a powerful new NHS inspectorate has stepped down from his job just weeks after being appointed.
Mr Homa has been chief executive of CHI since 1999
Peter Homa was named as the first chief inspector of the Commission for Healthcare Audit and Inspection (CHAI) in February.
He has now resigned from the post at the request of the organisation's chairman Sir Ian Kennedy.
The resignation will be seen as a set back for the government's plans to raise standards across the NHS.
Mr Homa was arguably the best qualified man for the job. He has served as chief executive of the current inspectorate, the Commission for Health Improvement, since it was established in 1999. He is expected to continue in that post.
A personality clash between Mr Homa and Sir Ian is believed to be the cause of his departure from the £165,000 a year post.
In a statement, he said: "Although, unfortunately, there were differences in approach, Sir Ian and I share the passion that CHAI should be a major force for the improvement of healthcare for patients."
Sir Ian said: "Peter is an outstanding figure in improving healthcare and has a huge amount to offer. I wish him every success."
Just week's ago, Sir Ian, who chaired the inquiry into the Bristol heart scandal, hailed Mr Homa's appointment as chief inspector.
There were differences in approach
Speaking in February, Sir Ian said: "I'm delighted that Peter has agreed to take on this new and exciting challenge. He is uniquely qualified and shares my determination that CHAI will be a force for improvement for patients."
Mr Homa's resignation has been greeted by dismay within the NHS.
Dame Deirdre Hine, a former chief medical officer for Wales and chairwoman of CHI, described it as a serious setback.
"I am saddened and concerned to learn that Peter Homa is not now to take up his post as chief inspector of the Commission for Healthcare Audit and Inspection, to which he was appointed only weeks ago.
"It is a serious setback for CHAI to have lost a chief officer of Peter's calibre at this early stage of its life.
"I have had the privilege of working with Peter as my chief executive for the past three and a half years.
"During that time we have broken new ground in establishing, for the first time, a body to which the NHS is required to account for the quality of the service it provides to patients.
"It is my view, and that of the CHI commissioners, that Peter's personal qualities of leadership and integrity and his unrivalled experience and expertise in the management of NHS organisations, and of CHI, made him the obvious and ideal choice for the chief inspector post in CHAI.
"We feel that he will be very difficult to replace in this role. He remains the much admired and respected Chief Executive of CHI."
Dr Gill Morgan of the NHS Confederation, which represents health service managers, said: "Peter Homa made a major contribution to NHS management and we are sad to see him go. We hope he will continue to contribute to the service and that his talents won't be lost."
She added: "It is important that momentum will be maintained and we hope that this setback will not interrupt the transition to the new organisation at this crucial stage."
CHAI is scheduled to start work in April next year. It will be responsible for carrying out inspections and ensuring standards are being maintained in NHS organisations across England and Wales.
It will take over the work of CHI, the Mental Health Act Commission, the National Care Standards Commission and some of the work carried out by the Audit Commission.
Sir Ian was appointed shadow chairman of CHAI in December last year.