Finance Minister Mathias Cormann (Image: AAP/Lukas Coch)

Mathias Cormann's campaign to become the next secretary-general of the Organisation for Economic Co-operation and Development (OECD) is running into trouble. Serious trouble.

Far from Australia pushing ahead on a unity ticket behind the former finance minister, former Labor foreign affairs minister Bob Carr has written to scores of international government contacts urging them to consider Australia's inaction on climate change before appointing Cormann.

He's not alone in his reservations, with politicians, former bureaucrats and journalists rallying against Cormann, calling him a hypocrite and a chameleon.