From 1993 to 1997, Romanoff worked as a senior associate at the consulting firm of Greenberg Baron Simon & Miller. Romanoff served as a senior policy advisor to Governor Roy Romer from 1997 to 1999.
Romanoff has taught government at the University of Colorado Denver (1999), the Community College of Denver (1996-2005), Metropolitan State College of Denver (1996-2005), and Red Rocks Community College (1996-2005).
Romanoff was a member of the Colorado House of Representatives from 2000 to 2008, winning re-election three times. Romanoff became Speaker of the House in 2005, and at the time was the youngest speaker in the history of the Colorado House. Before becoming speaker he was the House Minority Leader, representing House District 6. Romanoff was considered by many to be a possible Democratic candidate for Governor of Colorado in 2006, but announced in late 2005 that he would not seek the Democratic nomination for governor. Romanoff left the Colorado House after 2008 due to term limits.
On September 27, 2009, Michael Riley of the Denver Post reported that Romanoff was offered a position in the Obama Administration in exchange for not running for U.S. Senate against Michael Bennet. According to Riley, Jim Messina, deputy Chief of Staff to President Barack Obama, made a phone call to Romanoff offering him various positions in the Obama Administration, which included a position at the United States Agency for International Development. Romanoff turned down the offer.
On June 10, 2010, KDVR reported that Bennet said he had known about the White House's offer to Romanoff.
On October 8, 2014, the Aurora Sentinel endorsed Romanoff. On October 10, Politico reported that national Democrats are canceling more than a $1 million in campaign ads in support of Romanoff, "a sign of waning confidence in his prospects."
A preference poll taken March 16 at precinct caucuses showed Romanoff with 51 percent support, Bennet with 42 percent, and the remaining uncommitted. Delegates at each stage of the Democratic caucus-assembly process aren’t pledged to a candidate but are selected based on candidate preference.
