Crit Luallen is Kentucky's 56th lieutenant governor after a private swearing-in ceremony at the home of a retired Kentucky chief justice.
Democratic Gov. Steve Beshear chose Luallen to replace outgoing Lt. Gov. Jerry Abramson, who resigned to take a job as deputy assistant to President Barack Obama at the White House.
The former Democratic state auditor who has twice declined runs for higher office, Luallen has worked for six governors with positions including budget director and secretary of the finance and tourism cabinets.
Former Kentucky state auditor Crit Luallen says she will not run for governor in 2015.
Luallen has been mentioned as a possible Democratic contender as Democratic Gov. Steve Beshear finishes his second term.
In a written statement, Luallen said Thursday she is passionate about Kentucky's future but decided not to run because it was the best decision for her family.
Luallen's decision could open the door for Attorney General Jack Conway, a Luallen ally, to seek the Democratic nomination. Current state Auditor Adam Edelen is also considering running for governor. Republican Hal Heiner is the only person to officially announce as a candidate.
Democratic House Speaker Greg Stumbo has asked Democrats to delay their candidacies until after the November elections, in which Alison Lundergan Grimes is running for U.S. Senate and Democrats are trying to keep control of the state House of Representatives.
Former Auditor Crit Luallen says she will not challenge Republican U.S. Senator Mitch McConnell in 2014. Luallen has long been considered to be among the best-situated Democrats to unseat McConnell. She served two terms as auditor and many political observers credit her with raising the office's profile during her tenure.