The school at Ulster University’s Magee campus was meant to open this year.
But Ulster University said it is being delayed by the lack of devolved government.
Lord Alderdice told BBC Radio Foyle he believes the medical school could be signed off in Westminster.
“I have the sense that on specific issues, not whole areas like the management of the health service, but on specific issues, and this is a very specific one – the development of a medical school in the north west, we may be able to persuade government to take action in London over the heads of elected reps in Northern Ireland.”
He said it may be that approval for the school would need to see “a small bill to be passed” but said it is not impossible if there is a “will and determination”.
On Monday NIO Minister Lord Duncan told peers the school’s first step “will necessarily be taking forward the examination of the business case”.
A business case has been submitted to the Department of Health (DoH) in NI but it remains at an outline stage.
Ulster University (UU) said it had “submitted a complete outline business case on 21 October” and continued to work “proactively” to develop the project.
“Our responses to any remaining clarifications within the Graduate Entry Medical School business case were submitted to the Department of Health in October, following prompt and close engagement with the department and other relevant partners,” a spokesperson said.
“As the Department of Health has previously confirmed that any decision on funding can only be made by ministers, the university is not actively recruiting medical students
“If funding was confirmed, all other elements of the proposal for our graduate entry medical degree programme have been firmly on track.”
DoH said work was continuing on “the outline business case, and we cannot comment on the detail of this until it is completed”.
The only medical school in Northern Ireland at present is at Queen’s University in Belfast.
It is hoped about 60 doctors will train in Derry in the school’s first year, rising to 120 students per year within its first five years.