Sen. Kamala Harris (D-CA) was the most liberal member of the U.S. Senate in 2019, according to a ranking by GovTrack, an organization that tracks federal legislation and the votes of members of the U.S. Congress.
According to GovTrack, Harris ranked just above Sen. Bernie Sanders (I-VT), who openly identifies as a democratic socialist and is ranked in second place. The organization's 2018 ideology score pinned Harris as the fourth most liberal member, based on her record of voting and bill sponsorship in her first two years in the Senate.
In January 2019, Harris expressed support for the radical "Green New Deal" proposed by Rep. Alexandria Ocasio-Cortez (D-NY). The deal calls for the elimination of fossil fuel use in the country by the year 2030. She also supported Sanders' "Medicare for All" proposal, which would eliminate private health insurance in the U.S.
Harris later said she does not support eliminating private health insurance, but has not clarified how she would reconcile that with Medicare for All.