In 1991, Chaisson was elected to the Louisiana House of Representatives from District 56 in St. Charles Parish. In the primary on October 19, 1991, he trailed the Democratic incumbent, Ralph R. Miller, 7,104 to 6,570. The remaining 1,780 votes went to Emile J. Garlepied, another Democrat. In the November 16 state-wide election, Chaisson unseated Miller, 9,023 to 8,604. Chaisson won his second term in the state house in 1995 when he defeated Republican Robert "Bobby" Riggs, 9,759 to 5,736 in the primary.
In 2000, Chaisson was elected to the Louisiana State Senate representing Senate District 19 in St. Charles Parish. In the nonpartisan blanket primary held on October 23, 1999, Chaisson unseated fellow Democrat Ron Landry in the Senate election20,906 to 18,778. Chaisson was thereafter unopposed in the senatorial primaries of 2003 and 2007.
Louisiana State Senate president
On January 14, 2008, Chaisson assumed the leadership position in the senate as President of the Louisiana State Senate. Chaisson succeeded the term-limited Senate President Donald E. Hines, a Democrat physician from Bunkie in Avoyelles Parish in south central Louisiana. He was preferred for the Senate presidency by GovernorBobby Jindal, a Republican. In Louisiana, the state House Speaker and Senate President are normally suggested by the governor even if the governor's party or faction lacks a majority in the respective chamber. Chiasson and Republican senator, Michael J. Michot of Lafayette, had sought the Senate presidency. At that time, the senate had a Democratic majority of 23 to 16, but Chaisson indicated that he would seek "bipartisanship" in a bid to work with Governor Jindal and Republican lawmakers. Governor Jindal then deferred to the Democratic majority as Chaisson promised cooperation. Due to a series of party switches during Chaisson's tenure, the Senate became a Republican majority for the first time since Reconstruction. During Chaisson's tenure as Senate President, his leadership counterpart in the Louisiana House was Republican SpeakerJim Tucker of the New Orleans' suburb of Terrytown, Louisiana. Governor Jindal preferred that Tucker would become House Speaker even though at the time the house had a slight Democratic majority. Gubernatorial preference plays a major role in deciding leadership positions in the Louisiana legislature, so Tucker was selected despite a Republican minority in the House. During Tucker's tenure as speaker, the House also became a Republican majority similar to the Senate. Will Sentell of the Baton Rouge Morning Advocate Capitol News Bureau wrote in 2007 that Chaisson's career is "one of beating long odds." Chaisson has the support of the Louisiana Association of Business and Industry. However, he is not a firm ally of social conservatives in the legislature. In 2009, he was involved in a conflict between the Louisiana Senate leadership and the House on budget priorities, see cuts to higher education. Ineligible to run for the state Senate due to term-limits, in the primary held on October 22, 2011, Chaisson was succeeded by Gary Smith, Jr., who also followed him in the House twelve years earlier. Smith polled 16,501 votes to defeat the Republican Garrett C. Monti, who trailed with 11,215 votes. With Chaisson ineligible to run for office, on October 25, 2011, Governor Jindal tapped John Alario of Westwego in Jefferson Parish, whom the Republican Party had vigorously opposed in the 2007 senatorial campaign, as his choice to succeed Chaisson as State Senate President, effective January 2012. Alario became only the second person in Louisiana and United States history to have been the presiding officer of both the state House and the state Senate since the death in 2005 of Senator John Hainkel of New Orleans.
