US Senator Elizabeth Warren has edged past former Vice President Joe Biden for the first time in a major national opinion poll for the Democratic presidential primary race.
A survey by Quinnipiac University showed Warren polling at 27 percent among Democrats and independent voters who lean Democratic, with Biden polling at 25 percent.
US Senator Bernie Sanders, previously seen as part of a top three of Democratic presidential candidates, had 16 percent.
However, Warren’s two percent lead over Biden was within the margin of error.
The results marked a significant shift from prior polls for the Democratic nominating contest to choose a candidate to take on US President Donald Trump in the country’s presidential election next year.
Biden had been ahead of Warren by double digits since it began polling in March and by 13 points in the same poll in August.
“We now have a race with two candidates at the top of the field, and they’re leaving the rest of the pack behind,” said Quinnipiac polling analyst Tim Malloy.
Recent polls have shown rising support for Warren’s platform of what she calls “big structural change,” including proposals to expand social security and to tax wealthy Americans worth more than $50 million.
Biden, who served as vice president in the administration of former President Barack Obama, has for months led a crowded field of Democratic candidates and still leads in averages of national polls.
The Quinnipiac poll was conducted from September 19-23, just as allegations emerged that Trump urged Ukraine’s president to smear Biden and damage his candidacy.
A Reuters/Ipsos opinion poll taken on September 23-24 found a 1 percentage point rise in support for Biden since last week, suggesting his supporters were standing by their candidate.
Since launching his bid for 2020 presidency, the veteran politician has been referred to as "Sleepy Joe" by Trump, among other cases of name-calling.
The 76-year-old has also been lambasted for what his opponents and others have deemed inappropriate touching, hugging and sniffing of women and children. Biden has dismissed such allegations.