Oliver was re-elected as a UFO MLA in the 1929 election and was the sole (and last) United Farmers member in the legislature until 1941.

[1] Oliver quit the cabinet in late October 1942, in protest against Hepburn's leadership of the Liberal Party.

Oliver rejoined the cabinet under new Premier Harry Nixon as Deputy Premier, but Nixon's government was short-lived, going down to defeat in the October 1943 election placing third behind the victorious Progressive Conservatives and the Co-operative Commonwealth Federation which became the Official Opposition.

However, Thomson was unable to win election to the legislature, so Oliver remained house leader.

Oliver became party leader again from 1954 until 1958, including the 1955 election, but resigned due to caucus feuding.