Macnab became president of the League of Women Voters of Florida in 2009, where she spearheaded petitions for fair voting districts in Florida, tax reform and voter protection, and worked towards opening a dialogue with Cuba by organizing several delegations to the country. During her tenure as LWVFL president, two state constitutional amendments ending gerrymandering were finally accomplished, after 60 years of work by the Florida League. Under her presidency, the LWVFL announced a lawsuit in April 2014, protecting Florida voters from being purged from voter rolls within 90 days of a federal election, and she was asked to talk about it on The Daily Show. The state eventually decided not to purge the voter rolls. During her leadership, serious restrictions on voter registration drives were imposed and eventually removed because of the League's work. It eliminated roadblocks to voting by demanding the Florida Legislature re-institute early voting days, and the Sunday before election day, following long delays, including eight-hour lines in Miami, that voters faced during the 2012 Presidential election. The LWVFL also pushed for fairly-drawn congressional districts and saw fair districting upheld and implemented in 2014. Deirdre Macnab was nominated for the National Slate of the League of Women Voters of the United States in 2014, and was then nominated to be their National President in 2015. Her bid for the presidency was unsuccessful. She is generally credited with having as well as many state policies during her long tenure as president. Her latest initiatives include lobbying for the implementation of civil citations as a way to and reduce youth arrests. She heads the campaign to take Florida to the number one position in rooftop solar and harness the sun to truly make Florida the . As League Solar Chair, she educated the voting public about two 2016 ballot amendments, helping defeat one and pass the other. is her most recent push, educating people about the benefits of zero emission electric cars or "EVs".
Honors and awards
In 2012, Macnab was awarded the 2012 Florida Achievement Award by the Florida Commission on the Status of Women. The Orlando Sentinel named her the Most Influential Central Floridian of the Year the same year. In 2013, she was recognized by La Prensa Florida as a Community Champion during their annual Mujeres Destacadas Awards. She was recognized for her leadership and placed in the Congressional Record in 2014. In 2015, Audubon Florida honored her with the Women in Conservation award.