The Democratic presidential field continues to shrink. The latest casualty is California Senator Kamala Harris, who withdrew from the 2020 race on Tuesday. Earlier, Montana Governor Steve Bullock also ended his campaign. Former Vice President Joe Biden leads a cluster of four contenders near the top of national public opinion polls, but there is still plenty of uncertainty about where the Democratic race is headed as the campaign heats up. VOA National correspondent Jim Malone has more from Washington.