 Gaining a public reputation for financial expertise, he was active in the Federationist cause and was a delegate to the 1897 Constitutional Convention, where he was a significant figure in the development of Commonwealth finance schemes.After assisting the successful "Yes" campaign for the 1898 referendum, he was elected to the Senate in 1901 as a Free Trader.As a senator, Walker continued to focus on finance, although his views on social policy sometimes saw him on the outside of his party.