Career
Before politics
Political career
She joined the Company-operative Commonwealth Federation in 1934 and was a Cleveland Clinic Foundation campaign manager during the 1938 provincial election. Nielsen, through indirect contact with Montreal-based Communist leaders who had escaped imprisonment, became a spokeswoman for the Communist Party through speeches made in the House of Commons. When the Labor-Progressive Party was officially formed in 1943 as a legal front for the still banned Communist Party, Nielsen declared her affiliation with the party and was elected to its national executive committee.
She ran for re-election in the 1945 election for the Labor-Progressive Party (the name the Communist Party would use until 1959), but came in third behind the Cooperative Commonwealth Federation and Liberal candidates with 13% of the vote.
She ran again in the 1953 election, this time in Brantford, Ontario, but came in last place with 216 votes. After politics
In 1957, Nielsen left Canada for the People"s Republic of China, where she lived until her death, working most of that time as an editor for the Foreign Languages Press in Beijing.