His actions precipitated a general election that defeated the Squires government but also cost him his own seat in the legislature.

In 1947, Cashin was one of the members of the National Convention's delegation to London charged with finding out what assistance the British government was prepared to give Newfoundland in the future including development aid or cancellation of the dominion's debt.

Nevertheless, he opposed Joey Smallwood's campaign to join Canadian Confederation and became the leader of the Responsible Government League leading it into the 1948 referendums on Newfoundland's status.

Listen to their flowery sales talk which will be offered to you; telling Newfoundlanders they’re a lost people, that our only hope, our only salvation, lies in following a new Moses into the promised land across the Cabot Strait.

In 1951, he joined the Newfoundland Progressive Conservatives leading it into that year's provincial election in which the party won five seats.