RealClearPolitics' latest aggregate of polls depicts a similar portrait of the race as the new CNN/Des Moines Register poll. Elizabeth Warren, who has the support of 17% of likely Democratic caucus-goers.
In Iowa, which will vote on 3 February, Biden has slipped to a virtual tie with Sanders, according to modelling by the FiveThirtyEight website. The margin of error is plus or minus 4.9 percentage points.
As close as the race is, the results are welcome news for the Vermonter, whose prospects were thrown into doubt only a couple of months ago after he was hospitalized for heart surgery.
Joe Biden received some good news ahead of what promises to be a challenging Iowa caucus: a poll released on Saturday that shows him the overwhelming favourite for the Democratic presidential nomination among black Americans.
The poll was bad news for Buttigieg, who has dropped precipitously in Iowa since he was at the top of the field in that state in November. And for Biden, it suggested that he has not yet built the momentum to create the aura of inevitability he wants. The poll was released on Saturday - almost two months before the SC primary, which stands as the first real test of black support in the Democratic primary. She also has the advantage of a robust campaign infrastructure and strong network of activists in Iowa.
The three other top-tier candidates meanwhile fell closely behind him, clustering in a neck-and-neck competition for second place with Sen. Amy Klobuchar of Minnesota will be next to Buttigieg.
The findings are also discouraging for others, particularly New Jersey Sen. Cory Booker, D-N.J., at 3 percent. Booker, after campaigning aggressively in Iowa for almost a year, has support of just 3% of likely caucus-goers, according to the poll.
The results come just days from next week's Democrat debate in Des Moines, Iowa.
The remainder of candidates polled below 10 per cent.
U.S. Senator Bernie Sanders has taken a narrow lead among Democratic presidential candidates in the important early-voting state of Iowa in a tight battle with three rivals, a poll released by the state's largest newspaper showed on Friday.
"No one deserves to be our Democratic nominee unless they are able to build a broad and diverse coalition of voters", said Vedant Patel, spokesman for Biden's campaign in Nevada, citing endorsements and support from the Latino, black, Asian and Pacific Islander communities.
The poll still found room for movement among the candidates.