Poll: Biden supporters warm to Warren as an alternative

A new poll shows that former Vice President Joe BidenJoe BidenMellman: Trump voters cling to 2020 tale FDA authorizes another batch of J&J vaccine Cotton warns of China collecting athletes' DNA at 2022 Olympics MORE’s supporters are starting to warm up to Sen. Elizabeth WarrenElizabeth WarrenProgressives rave over Harrison's start at DNC On The Money: Schumer to trigger reconciliation process on Wednesday | Four states emerge as test case for cutting off jobless benefits Big Tech critic Lina Khan named chair of the FTC MORE (D-Mass.) as a viable alternative, though Sen. Bernie SandersBernie SandersProgressives rave over Harrison's start at DNC Zombie Tax punishes farmers to fill DC coffers Progressives threaten to block bipartisan infrastructure proposal MORE (I-Vt.) is still the preferred second choice. 

The Hill-HarrisX poll released on Monday found that 20 percent of likely Democratic voters who support Biden would support Warren as their second choice, which marks a 12-point increase from when an identical poll was conducted in May.

However, Sanders still remains the top second-choice candidate among Biden supporters at 35 percent, an 8-point increase from the May 3-4 poll.

Another 10 percent of Biden supporters said they would back Sen. Kamala HarrisKamala HarrisDemocrats learn hard truths about Capitol breach Harris calls for pathway to citizenship for Dreamers on DACA anniversary Abbott says he'll solicit public donations for border wall MORE (D-Calif.), a 5-point dip from the last poll. Former Rep. Beto O’Rourke (D-Texas) garnered 5 percent support, a 6 point fall. South Bend, Ind., Mayor Pete ButtigiegPete ButtigiegHigh-speed rail getting last minute push in Congress Buttigieg: Bipartisan deal on infrastructure 'strongly preferred' OVERNIGHT ENERGY: Biden ends infrastructure talks with key Republican | Colonial Pipeline CEO grilled over ransomware attack | Texas gov signs bills to improve power grid after winter storm MORE (D) followed, dipping to 7 percent from 10 percent.

Other polls have shown similar results.

According to a weekly Morning Consult data tracker, 25 percent of Biden's supporters said they backed Sanders as their second choice, compared to 20 percent who chose Warren as their next favorite. Harris was named as the second option by 14 percent, according to the poll's latest figures that were updated last week. 

The survey comes as the Democratic primary heats up, though signs are emerging that the race is becoming a four-way race between Biden, Sanders, Warren and Harris.

The Hill-HarrisX survey was conducted among 138 Democratic and Democratic-leaning Biden supporters between Aug. 16 and 17 with a margin of error of plus or minus 8 percentage points.

—Tess Bonn