The "public option" for health insurance, as defined by the 111th Congress, grew from roots planted in California in 2001. Progressives supported it as a voluntary transition toward single-payer insurance, while conservatives opposed it as a government "takeover" of health care. Although present in several interim bills and in legislation passed in November 2009 by the House of Representatives, the public option was omitted from the legislation passed by the Senate in December 2009 and from the final package adopted by both houses in March 2010. Lack of support among moderate Democrats, opposition from Republicans, and ambiguous messages from the White House are among the explanations for the public option's defeat. However, there is nothing in the recently enacted legislation that would prohibit states from creating a public option in their exchanges.