In 1968, Hamilton was elected to the
Tennessee Senate from District 24, representing much of the northern part of
West Tennessee. He served in an increasingly important series of positions on committees and in party leadership posts, culminating with his selection as majority leader in 1977, a position which he was to hold for 10 years. In 1987, a rebellion within the Democratic Caucus began over the largely
conservative leadership and style of Senate
Speaker and
Lieutenant Governor of Tennessee John S. Wilder, a close Hamilton friend and ally, which resulted in the nomination by the Democrats in the 1987 organizational session of the legislature of
Riley Darnell of
Clarksville, Tennessee, for Lieutenant Governor and Speaker. However, Hamilton led a faction of eight other Democratic senators who remained loyal to Wilder, and along with unanimous support from the
Republican senators, this coalition voted to retain Wilder. The nine dissident Democrats were then dismissed from the Democratic caucus and reorganized as their own group, which they styled the "New Democratic Caucus", with Hamilton as their leader. Hamilton and his allies maintained some positions of leadership in the Senate, with others being filled by Republicans. Hamilton chaired the all-important Calendar Committee, and remained on other influential committees, most notably Ways and Means. While in the state senate Hamilton was very active in the
National Conference of State Legislatures. He was also very active in the state's conservation efforts with regard to
Reelfoot Lake, which was located in his district and served as an important source of
tourism as well as an important aquatic and wildlife resource. In 1994 Republican
Don Sundquist was elected
governor of Tennessee and the Republican representation in the state senate increased to 15, just two short of a majority. On September 15, 1995, Hamilton and another Democratic senator who had also been a traditional Wilder ally made the decision to
switch parties, giving the Republicans their first majority in the Tennessee Senate since
Reconstruction, and Hamilton again became majority leader, although now of the other party. However, the Republican majority was short-lived as Hamilton did not choose to run for reelection in 1996, and the senate reverted to Democratic control. ==Commissioner==