For its first two years, the Iowa General Assembly failed to choose Iowa's first U.S. Senators, due to a three-way split that prevented any candidate from earning the required number of 30 legislators' votes. However, after the 1848 elections gave the Democratic Party a greater share of Iowa legislators, Dodge (and George W. Jones) were elected as Iowa's first two U.S. Senators. By drawing lots, Dodge received the seat with the shorter term (to expire in 1849), but was re-elected that year to a full six-year term. While in the Senate, he served as chairman of the Committee to Audit and Control the Contingent Expenses (in the Thirty-first and Thirty-second Congresses), the Committee on Pensions (in the Thirty-first Congress), the Committee on Revolutionary Claims (in the Thirty-second Congress), and the Committee on Public Lands (in the Thirty-third Congress).