Poll: Biden supporters warm to Warren as an alternative

A new poll shows that former Vice President Joe BidenJoe BidenGiuliani clashes with CNN's Cuomo, calls him a 'sellout' and the 'enemy' Giuliani says 'of course' he asked Ukraine to look into Biden seconds after denying it Trump whistleblower complaint involves Ukraine: report MORE’s supporters are starting to warm up to Sen. Elizabeth WarrenElizabeth Ann WarrenOvernight Health Care — Presented by Partnership for America's Health Care Future — Pelosi unveils signature plan to lower drug prices | Trump says it's 'great to see' plan | Progressives pushing for changes Buttigieg calls Warren 'evasive' on Medicare for all Sanders hits 1 million donors MORE (D-Mass.) as a viable alternative, though Sen. Bernie SandersBernie SandersOvernight Health Care — Presented by Partnership for America's Health Care Future — Pelosi unveils signature plan to lower drug prices | Trump says it's 'great to see' plan | Progressives pushing for changes Krystal Ball calls on Sanders to follow Yang's lead on war on drugs Buttigieg calls Warren 'evasive' on Medicare for all 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 Devi HarrisTwo former Congressional Black Caucus chairmen back Biden Strippers, 'Hustlers' and the Democratic debates 2020 Dems honor Emily Clyburn 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 ButtigiegPeter (Pete) Paul ButtigiegOvernight Health Care — Presented by Partnership for America's Health Care Future — Pelosi unveils signature plan to lower drug prices | Trump says it's 'great to see' plan | Progressives pushing for changes Buttigieg calls Warren 'evasive' on Medicare for all Overnight Energy: Trump officials formally revoke California emissions waiver | EPA's Wheeler dodges questions about targeting San Francisco over homelessness | 2020 Dems duke it out at second climate forum 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