Sen. Bernie Sanders has taken sole possession of the lead in the Democratic primary race, a new Wall Street Journal/NBC News poll finds, with four candidates essentially tied for second place amid declining support for former Vice President Joe Biden and the rising profile of Michael Bloomberg, the former New York mayor.

Sanders had 27% support among Democratic primary voters nationally in the new survey, the same as in January. Biden, who previously had 26%, has dropped 11 percentage points since last month. Biden is bunched closely with Bloomberg and Sen. Elizabeth Warren, who each have 14% support, and former Mayor Pete Buttigieg, with 13%. Sen. Amy Klobuchar has 7%.