In April 2013, Rep. Sullivan became the second Republican representative in Illinois to support the state's same-sex marriage bill.
[4][5][better source needed] Rep. Sullivan Jr. served as Assistant Republican Leader for the 98th session of the Illinois General Assembly.
[2][better source needed] His committee assignments included Executive, Consumer Protection, and Rules where he was the "Republican Spokesperson" (ranking minority party member), as well as Mass Transit, Public Utilities, and Revenue and Finance.
[citation needed] He was one of two Republican representatives in Illinois to support a same-sex marriage bill in April 2013.
[6] The Illinois branch of the Republican-associated Opportunity Project (IOP), a self-described "research and public policy enterprise" advocating conservative state legislation and policies in support of "free markets and free minds" [a 501(c)(4) tax exempt organization], scored Rep. Sullivan Jr. in 2012 at 88 on a scale of 100; a grade of "A−", it was a score tied for 3rd highest of the 120 members of the Illinois House evaluated.