He came to prominence inside the SNP through his activities in the left-wing 79 Group and became a party office bearer. In the 1980s he led the SNP campaign in opposition to the Poll Tax. It was widely known that he politically disagreed with the former SNP leader Alex Salmond and he was at one stage viewed as belonging to the SNP Fundamentalist camp. He allied himself to figures such as Jim Sillars and Alex Neil within the party.
However, upon becoming a Member of Scottish Parliament (MSP) he moderated his political position, eschewing his former leftist stance and adopting a gradualist approach to Scottish independence in place of his previous fundamentalist position. He has been one of SNP leader John Swinney's closest supporters.
In 2000 he ran for the post of SNP Senior Vice-Convenor (the party deputy leader) but lost to Roseanna Cunningham.