NEW YORK, Feb 10 — Support for former Vice President Joe Biden's US presidential bid has tumbled nationally following a lacklustre finish in last week’s Iowa caucuses, while interest is surging among Democrats and independents for the upstart candidacy of billionaire media mogul Michael Bloomberg, according to a Reuters/Ipsos public opinion poll released yesterday.

The February 6-10 poll found that 17 per cent of registered Democrats and independents said they would vote for Biden, down five percentage points from a similar poll that ran last week before Iowa held its first-in-the-nation nominating contest.

US Senator Bernie Sanders led other candidates in the poll with 20 per cent support, up one point from last week, while 15 per cent supported Bloomberg, an increase of six points.

Another 11 per cent backed US Senator Elizabeth Warren, 8 per cent supported former South Bend, Indiana Mayor Pete Buttigieg, 5 per cent said they would vote for New York businessman Andrew Yang and 3 per cent supported US Senator Amy Klobuchar.

The poll underscores what has been a steady decline in support for Biden, who until recently was considered the favorite to win the highly contested race for the party's nomination.

Biden's primary appeal to voters has been his claim to be the most electable of all of the candidates. Yet he finished in fourth place in Iowa, behind Sanders, Buttigieg and Warren. And the Reuters/Ipsos poll shows that Democrats and independents are now just as likely to believe that Sanders can win the White House in the November 3 election as they are Biden.

When asked which candidate was "most likely to beat President Trump,” 21 per cent picked Biden, which is down nine points from last week. Another 21 per cent said Sanders had the best chances to win, and 15 per cent said it was Bloomberg.

Bloomberg, who has not participated in the nationally televised debates and will not be on the ballot in many of the early statewide nominating contests, has instead banked his candidacy on his comparatively strong name recognition and millions of dollars of personal expenditures into campaign advertising.

The poll found that Bloomberg would beat Trump by four points among registered US voters if the two were running against each other in November's presidential election. In comparison, Sanders also would beat Trump by four points and Biden would beat Trump by two points.

The Reuters/Ipsos poll was conducted online, in English, throughout the United States. It gathered responses from 952 registered voters, including 556 who identified as Democrats or independents. The poll has a credibility interval, a measure of precision, of about five percentage points. — Reuters