Taggart, who was a Democrat, became active in local politics in Indianapolis in the 1880s. He was elected auditor of heavily Republican Marion County in 1886, reelected in 1890, and served in that capacity until 1894. During that time Taggart also served as the Democratic Party chairman at the city, county, and state levels. As the county chairman during the presidential campaign of 1888, his efforts helped Grover Cleveland carry Marion County over native son Benjamin Harrison, the first time the county had voted Democratic in a Presidential election. As state chairman in 1892, Taggart helped Cleveland carry Indiana to challenge Harrison's bid for reelection.