Joe Biden, Barack Obama's Vice-President, has emerged as an early frontrunner among Democrats vying for the 2020 presidential nomination.
He has a dominant lead among voters in Iowa, who will be the first to state their preference next year.
A new CNN/Des Moines Register/Mediacom poll finds 32 per cent of likely caucusgoers saying they back Biden as their first choice.
That's ahead of 19 per cent for former presidential candidate Senator Bernie Sanders and 11 per cent for Congressman Beto O'Rourke, the telegenic campaigner who came close to an against-the-odds win in Texas last month.
The results have Democrats salivating about a dream ticket that matches a 76-year-old veteran, who is popular with blue-collar voters, with O'Rourke, a 46-year-old with a knack for producing viral videos.
However, he has done little to dispel the speculation and has touted his age as an advantage.
"I'll be as straight with you as I can. I think I'm the most qualified person in the country to be president," he said during a speech at the University of Montana this month.
"The issues that we face as a country today are the issues that have been in my wheelhouse that I've worked on my whole life."
His supporters say he is best placed to woo back the parts of the Rust Belt and middle America that were unimpressed with Hillary Clinton's run and defected to Donald Trump in 2016.
But doubts remain that the Democrats are in danger of losing the youth vote if they plump for Biden or the likes of Sanders, 77, or Elizabeth Warren, 69.
AP reported at the weekend that Biden was talking to friends and long-time supporters about whether he was too old to run for the White House.
A key question for former Vice-President Joe Biden to consider is whether he is too old to be president.
Profile | Joe Biden
United States Vice-President 2009 – 2017 Born: November 20, 1942 (age 76) Party:Democratic
Education:University of Delaware then Syracuse University Law College
Political history: Biden was senator for Delaware from 1973 until his appointment as Vice-President in 2009
Presidential ambitions:He ran for the Democratic Party nomination in 1988 and in 2008, dropping out both times due to poor showing in the primaries. He declined to run in 2016, following the death of his son. He has not ruled out campaigning in 2020, although this would make him by far the oldest presidential candidate in US history.
"A gaffe in Washington is someone telling the truth, and telling the truth has never hurt me" – Interview with Newsweek in 2008, referring to his reputation for making gaffes
Former US Vice-President Joe Biden has topped an early poll of Democratic candidates in Iowa.
They have floated the idea of teaming up with O'Rourke.
O'Rourke excited Democratic voters and individuals donors in Texas, a usually staunch Republican state.
The three-term Congressman initially ruled himself out of a 2020 run but is now considering capitalising on his sudden national profile.
He became famous for livestreaming almost every aspect of his life during the Midterm campaign when he came within three percentage points of a giant-killing victory over Senator Ted Cruz.
It represents the first votes of the election cycle as, come February 2020, party supporters gather in caucuses to select their preferred candidate.
The winner has gone on to clinch the nomination in every contested primary season since 2000.
Among other notable contenders, Warren, the Massachusetts Senator, polled 8 per cent and Kamala Harris, the California Senator, won the backing of 5 per cent of respondents in the new poll.
Last week the New York Times reported that Sanders and Warren had met to discuss their rival presidential ambitions, but that neither had tried to dissuade the other from running, nor had they agreed to a joint-ticket.
Warren, a noted progressive like Sanders, has drawn fierce criticism for publishing the results of a DNA test to prove that she has Native American ancestry.
The move followed Trump, who mockingly dubbed Warren "Pocahontas", alleging such claims were false.
Some takeaways from the new CNN/Des Moines Register poll ahead of 2020: ■ Rep. Beto O'Rourke is in prime position ■ Democrats love former first lady Michelle Obama ■ "Seasoned hand" beats "newcomer"
