Nicol first ran for office in the 1972 Ottawa municipal election, running for alderman in Elmdale-Victoria Ward. She ran on a platform of improving communications between city hall and the people, and to have a lawyer available to interpret city by-laws for free for the public. She supported building an arena and a community centre in her ward, encouraged opportunities for youth programs, re-establish local health clinics in the ward, a new day-care centre, better snow removal, road maintenance and supported a rapid transit system.[2] In the election, she placed third, with just over 1400 votes, losing by over 1100 votes to Walter Ryan.
Following Ryan's retirement as alderman, Nicol ran again for the seat in the 1974 Ottawa municipal election. Running on a platform of improved rapid transit, curbing urban sprawl and more recreational and daycare facilities in the ward, she won the seat, defeating three male candidates, including former alderman Rolly Wall in the process.[12] At the time of her election, Nicol was active in the Liberal Party, and was on the executive of the Ottawa and District Liberal Association.[10] During her time as alderman, she claimed to have "served on more committees and had a better attendance record than any other city councillor", and she "looked after her ward like a mother hen, fighting to keep citizens groups happy and fulfil her campaign promises". She gave herself credit for the approval of the Tom Brown Arena in Mechanicsville, the completion the "Ottawa Wset Plan" and the designation of Hintonburg for neighbourhood improvement grants. On council, she voted with the "right wing" bloc and was criticized as being the "developer's voice" due to her husband's job as a building contractor and her brother-in-law being the head of Tartan Development Ltd.[13]
Instead of running for re-election in her ward, Nicol opted to run for a seat on the Ottawa Board of Control in the 1976 Ottawa municipal election. Nicol ran on a "business sense" platform of reducing taxes by elimination some duplication in the various levels of government, stripping all regional government departments except planning, transportation and social services, increasing aid to employables spent on retraining programs. She was also opposed to the 'overbuilding' of roads which she felt disrupted communities.[13] In the election, Nicol won a seat on the board, placing third on the four-seat group. The election was the start of a rivalry with the more left wing Marion Dewar, deputy mayor of Ottawa, who won re-election to the Board of Control, winning the top spot. The two had been "embroiled in pre-election tangles".[14] During her time as a controller, Nicol was known for her "quick temper", but also her "political smarts". She would often get into arguments with her colleagues but "usually (didn't) lose".[15] Nicol was fiercely opposed to the Board's planned abolition, and was one of only two councillors to oppose a motion for its abolition in a 1977 vote.[16] Nicol sat as chairman of the city's procedures committee before resigning in 1977, after holding a press conference to accuse several aldermen of "deliberately circumventing established procedure to achieve their goals".[17]
Following the retirement of mayor Lorry Greenberg, Nicol opted to run for the city's top job in the 1978 Ottawa municipal election, rather than contest the Liberal nomination in the 1978 federal by-election in Ottawa Centre.[18] She ran because she felt the feeling of frustration with "inefficient municipal government ... is widespread". She believed she was speaking on behalf of the 'little guy', be they the small-business man thwarted by bureaucracy, or the tax-payer "choking on the hypocrisy of 'do-gooders'".[7] During the campaign, she was called a "dragon lady" live on-air by news anchor Ab Douglas of CBOT, who thought his microphone was off.[19] Nicol ran against her political rival, deputy mayor Marion Dewar, known for her ties to the social democratic New Democratic Party. The campaign was considered a "hard-fought battle", with Nicol driving the "city council's left wing into a fury with her partisan shots".[20] On election day, Dewar defeated Nicol by nearly 20,000 votes.
Citing public dissatisfaction with Dewar, Nicol announced in August 1980 that she would run against the mayor in the 1980 Ottawa municipal election in a re-match of the 1978 race. She accused Dewar of "indecisive leadership", "(failing) to bring more industry and jobs to Ottawa", and not "(balancing) expensive reforms with economic growth".[21] Nicol decided to change her image for her 1980 mayoral run, running as a "new person with a low-key, more positive style", claiming that she was "being herself" this time. She had cited that once of the possible reasons what she lost in 1978 was that she was not being herself.[22] Indeed, the Dewar-Nicol race of 1980 was less contentious than their 1978 battle, with Nicol running more a more centrist campaign. One of her main attacks was accusing the Dewar administration of inefficient management, bringing up the example of the city taking too long to pick a site for a new police station, which was also over budget. Among her promises in 1980 were bringing "businesslike leadership" to the mayor's chair, seeking government assistance to build an industrial park, more flights to Ottawa, building a bridge across the Rideau River at Hunt Club Road, and better daycare for working mothers.[23] Her new image barely made a dent in Dewar's margins however, as Nicol lost to her by over 16,000 votes.