WASHINGTON (Reuters) - U.S. Senator Elizabeth Warren on Wednesday edged past former Vice President Joe Biden for the first time in a major national opinion poll for the Democratic presidential primary, making her largest gains among white voters with a college degree.

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Warren drew 27% support to Biden’s 25% in a Quinnipiac University poll of Democratic voters and independent voters who lean Democratic, though her lead was within the margin of error.

The results marked a significant shift from Quinnipiac’s prior polls for the Democratic nominating contest to choose a candidate to take on President Donald Trump in November 2020. 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.

Senator Bernie Sanders of Vermont trailed the leaders at 16%, with Pete Buttigieg, mayor of South Bend, Indiana, at 7%. Kamala Harris, a senator from California, received 3%, her lowest support yet in the poll, Quinnipiac said.

Biden, a household name from his time as former President Barack Obama’s No. 2, has for months led a crowded field of Democratic hopefuls and still leads in averages of national polls.

The Quinnipiac poll was conducted from Sept. 19-23, just as allegations emerged that Trump solicited Ukraine’s help to smear Biden and damage his candidacy.

A Reuters/Ipsos opinion poll taken on Sept. 23-24 found a 1 percentage point rise in support for Biden since last week, suggesting his supporters were standing by their candidate.

But a flurry of state-level polls, conducted before the Ukraine story took hold of the news agenda, have shown rising support for Warren’s platform of what she calls “big structural change,” including proposals to expand social security and to tax fortunes worth more than $50 million.

Warren jumped to 27% support among Democrats and independents in the early voting state of New Hampshire, a Monmouth University poll released on Tuesday showed, a 19 percentage point rise since May. Biden’s support fell to 25% in the poll, a drop of 11 points since May.

In California, Warren led Biden 29% to 20% in a Berkeley IGS poll published on Wednesday. Last week, the Des Moines Register reported that Warren lead Biden by two points in its poll in Iowa, which holds outsized influence as host of the first presidential nominating contest next year.