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.

The CNN poll is the first fielded by the outlet in which Biden, 77, can not brag about being in first place outright.

Sanders, 78, and his fellow septuagenarian enjoy a significant, double-digit advantage on their closest competitors for the 2020 Democratic presidential nomination less than two weeks out from the Iowa caucuses.

Massachusetts Sen. Elizabeth Warren trails the duo with 14% support, while former South Bend, Indiana, Mayor Pete Buttigieg is at 11%. Meanwhile, former New York City Mayor Michael Bloomberg registers 5% support, compared to Minnesota Sen. Amy Klobuchar and entrepreneur Andrew Yang's 4% and hedge fund manager Tom Steyer's 2%.

Wednesday's poll coincides with another fielded by CNN and its partners in Iowa, which found Sanders with a slim lead over his rivals in the first-in-the-nation state.

Sanders's surge comes as he gains a better standing with voters who identify as liberal, while Warren, 70, fell with the same group. He's also now as popular with black Democrats as Biden, though the vice president took a hit in general enthusiasm for his candidacy, dropping to 34% in contrast to Sanders's 39%.

Forty-five percent of respondents told researchers Biden was still the most electable White House hopeful against President Trump in the fall, but only 24% felt the same way about Sanders.

The CNN poll surveyed 500 registered voters across the country via landlines or cellphones between Jan. 16 through Jan. 19. Its findings have a margin of error of plus or minus 5.3 percentage points.