[1] Carroll stepped down as minority leader in July 2015 to unsuccessfully run against incumbent Republican Mike Coffman for Colorado's 6th congressional district in the U.S. House of Representatives.

[9] Carroll first ran for the Colorado House of Representatives District 36 in 2004, defeating Republican Jim Parker 55%-45%.

[11] Carroll first ran for the Colorado State Senate District 29 in 2008, defeating Republican Suzanne Andrews 69%-31%.

[7] During her first year in office, she refused to discuss legislative issues with lobbyists during debate, a practice that led them to complain about her to the Democratic leadership.

[16] In 2013, Carroll and fellow Democratic Representative Rhonda Fields sponsored Colorado House Bill 1229, which mandates universal background checks for gun purchases in the state.

[5][28] Carroll was endorsed by Democratic Colorado Governor John Hickenlooper,[1] Planned Parenthood, NARAL Pro-Choice America, EMILY's List, the International Brotherhood of Electrical Workers, and the League of Conservation Voters.

[31] Americans for Prosperity, the conservative advocacy organization backed by the Koch family, alleged that Carroll had conflicts of interest while serving in the state senate.

The Denver Post rated the claim somewhat true and wrote that AFP's claim of a conflict of interest was not true in that Carroll had not benefited from the bill, but that the Colorado Ethics Board of the General Assembly had ruled that lawmakers should proactively disclose "potential" conflicts of interest.