Sanders, 76, and Warren, 70, have typically been close to each other, or Sanders has been above Warren, but the two polls show Warren received at least 9 percentage points more than Sanders and was much closer to Biden, 76, than Sanders.
Some 24 percent of respondents chose Warren while 28 percent chose Biden in an Investor’s Business Daily/TIPP poll conducted from Aug. 22 through Aug. 30 and released on Sept. 3.
That was an increase of 7 percent for Warren since a survey released in early August and a dip for Biden of 2 percent.
Sanders received 12 percent, the same as last month, and no other candidate received 10 percent or more. Sen. Kamala Harris (D-Calif.) received 6 percent to place her in fourth, down from 11 percent.
About 27 percent of female respondents opted for Warren, versus 28 percent who chose Biden. Biden saw the same support among men, while 19 percent of male respondents indicated support for Warren.
The poll was answered by 903 people but the questions pertaining to Democratic candidates included just 360 registered voters who are either Democrats or who lean Democrat.
An Economist/YouGov survey (pdf) conducted from Aug. 24 through Aug. 27 and released late last week showed 24 percent of respondents choosing Biden when asked who they would vote for if the Democratic presidential primary or caucus was held on the day they answered the question. Warren was second with 20 percent, ahead of Sanders’ 14 percent.
No other candidate received over 10 percent and 12 percent of respondents said they were not sure.
Warren saw the most support from male respondents while Biden received the most support from female respondents.
Additionally, when asked which Democratic candidates they’re considering and allowed to select all that applied, more people ticked Warren than any other candidate. Fifty-three percent of respondents said they are considering voting for Warren, versus 47 percent who ticked Biden and 41 percent who chose Sanders.
Sen. Kamala Harris (D-Calif.) was fourth with 35 percent and South Bend, Indiana Mayor Pete Buttigieg was fifth with 28 percent.
The survey was conducted among 1,500 voters but the questions were answered by about 570 respondents who said they will be voting in the primary or caucus for the Democratic primary.
The two polls followed a rash of polls that showed Biden with a strong lead. Most of them showed Biden in first by at least 10 percentage points.
A Quinnipiac University poll released Aug. 28, for instance, saw 32 percent of Democratic voters and independent voters who lean Democratic opting for Biden, followed by Warren at 19 percent, and Sanders at 15 percent.
A poll from Emerson showed the former vice president with 31 percent support, compared to 24 percent for Sanders, 15 percent for Warren, and 10 percent for Harris.
Emerson noted the age divide in the primary, with Sanders getting 36 percent support of those under the age of 50 compared to 11 percent support among those 50 and over. Biden, on the other hand, has the support of 21 percent of those under 50 and 44 percent of those 50 and over, while Warren saw a mix from both groups.