 His supporters attempted to have Barnewall chosen as Speaker of the House of Commons but he was defeated by the Crown candidate James Stanyhurst.Barnewall assumed the role of Leader of the Opposition, concentrating his assault on the composition of the House, which he alleged had been "packed" with Crown supporters; in particular he objected to the presence of certain English members who represented boroughs where they did not live, and which in many cases they had never even visited.He brought a legal challenge to the validity of the House's composition, but although the judges ruled in his favour on two technical points, he was not successful in excluding the absentee members, and Sidney was able to get his program of legislation through Parliament without serious difficulty.