On 26 March 2021, Sillars backed Alex Salmond's new Alba Party, saying: "This is a very welcome development as it gives the independence voters a party that is not the SNP – which many, including me, with justification, believe is tainted with political corruption, and which is grossly incompetent in a whole range of its activities from building ferries to building hospitals, and boasting about being the Saudi Arabia of wind, without creating jobs." He still remains a member of the SNP, but told Holyrood magazine's Politically Speaking podcast that he had not voted for them "for a long time". He said: "I didn't join Alba, and I won't join Alba. Alba and the SNP means the movement is split, and a split movement will not win. I'm hoping a change of leadership in the SNP is going to happen and I'm staying in the SNP, hoping to influence people, saying 'look, we've got to have a rapprochement with the people who left to join Alba.'"
