Blue's previous political involvement included service on a District Health Board as an elected member from the centre-right Citizens and Ratepayers Now organisation. She resigned from this shortly after being elected a National MP. In the 2005 general election, Blue stood as the National Party's candidate in the Mt Roskill electorate. She was unsuccessful in winning the traditionally safe Labour seat from high-profile Labour MP Phil Goff, but entered Parliament as a list MP, having been ranked 41st on the National Party list. In her first term as an Opposition MP, Blue had responsibilities as the spokeswoman for the National Party onwomen's issues, as well as associate health. Subsequent to her election to Parliament, Blue strongly advocated for further available health care for sufferers of breast cancer, including wider use of the anti-cancer drug Herceptin. In 2006, Blue's Human Tissue Amendment Bill was drawn from the member's ballot. The bill passed its first reading and was sent to select committee, but was defeated at its second reading. In 2008, Blue sought the National Party candidacy in Auckland Central electorate, where she has been a long-term resident. Blue lost the contest to the much younger Nikki Kaye who went on to win the seat. Blue was subsequently unsuccessful in standing against incumbent MP Phil Goff in Mt Roskill for a second time, but was returned to Parliament as a List MP at the 2008 election. In May 2010 Blue's Consumer Guarantees Amendment Bill, which extends the Consumer Guarantees Act to cover online auctions, was drawn from the member's ballot. It passed its first reading and was sent to select committee in July 2010. In November 2011, Blue stood for a third time in Mt Roskill against Goff, but was unsuccessful. She was returned to Parliament for a third time as a List MP. Blue was appointed Equal Employment Opportunities Commissioner at the Human Rights Commission in April 2013 and took up the position in June 2013. She resigned from Parliament and was replaced by Paul Foster-Bell. As Commissioner she urged New Zealand sporting bodies to "level the playing field" for women. In 2018 she told a UN committee before leaving the Human Rights Commission that successive governments have failed New Zealand women over domestic violence, the number one human rights issue. In the 2019 Queen's Birthday Honours, Blue was appointed a Member of the New Zealand Order of Merit, for services to women and the State.
