Prior to his election he worked in retail, property, as a college lecturer, a constituency assistant to Donald Gorrie MSP, and as a community care professional.
[citation needed] O'Donnell was a member of both the Scottish and Federal policy committees and held the position of Vice Convenor and Treasurer of the Central Scotland Liberal Democrats.
The leadership could no longer be regarded as "either Liberal or Democratic", he said, adding: "The greatest betrayal of all, of course, is the alliance formed in London between the Lib Dems and the Tories."
He said: "Since that fateful day, I have watched helplessly from the sidelines as this Government at Westminster has attacked every vulnerable group in Scotland, from carers to disabled students to migrants, with some of the most draconian policies I have ever seen in the name of cuts.
He also complained that the Scottish Lib Dem group had voted tactically against the SNP's proposed policy on minimum pricing on alcohol, rather than on principle.
"[4] The Scotland on Sunday[5] reported senior party figures were furious that O'Donnell did not speak to leader Tavish Scott before deciding to quit.