He became an instrumental figure in Tommy Douglas's Co-operative Commonwealth Federation government between 1944 and 1961, serving as Education Minister and then Treasurer.

In that role, Lloyd piloted Canada's first Medicare program from legislation to implementation, including resolving the 1962 Saskatchewan doctors' strike.

The 1944 election brought the CCF to power for the first time with the party promising to invest in social security and economic development.

After the CCF victory, In 1961, Douglas resigned as premier to assume the leadership of the newly-formed federal New Democratic Party (NDP).

[8] Lloyd's biggest obstacle was the July 1962 Saskatchewan doctors' strike, when the province's physicians withdrew service in an attempt to defeat the Medicare initiative.

[8] Lloyd and his government refused to back down on the concept of a universal public health care system and persuaded the doctors to settle after 23 days.

In that role he sought to renew grassroots engagement and party policy, which he felt had begun to stagnate after the long period in power.

[16] When the "Waffle" movement—a faction of New Left supporters seeking to return the NDP to its socialist roots and advocating against American imperialism—began making inroads into the NDP at both the federal and provincial level in the late 1960s, it found a supporter in Lloyd, who saw its potential to increase engagement and propose innovative policy.

[17][18] After a special caucus meeting in 1970 in which Lloyd judged he lacked the support of much of his cabinet, he decided to resign as party leader.

[20] Lloyd opted not to run in the 1971 election, which saw Blakeney guide the NDP back to a majority government on a rejuvenated platform that incorporated elements of Waffle policy and promised a return to the interventionist approach of the CCF.