Bernie Sanders has rocketed in popularity, joining Joe Biden in putting space between the top two candidates in the Democratic race for the White House and the rest of the pack, according to a new poll.

The Vermont senator attracted 27% support from Democrats or Democratic-leaning independents surveyed for a CNN poll conducted by SSRS, a bounce of 7 percentage points since December. Biden pulled in 24% support, meaning the pair are in a statistical tie given the study’s margin of error. The former vice president similarly grew his share of the vote, up 2 percentage points from last year.