Howard Dean has close links with the Liberal Democrats
Lib Dem leader Nick Clegg could be the surprise winner of the UK's general election, former US presidential candidate Howard Dean has said.
Mr Dean praised Mr Clegg as a "young, dynamic leader".
And he said he could be the big winner from Britain's first televised election debates, capitalising on disillusion with the two larger parties.
The UK's first-past-the-post voting system makes it difficult for a third party to break through.
The most likely outcome of a surge in support for the Lib Dems, who are currently trailing Labour and the Conservatives in the opinion polls and have far fewer MPs, would be a hung Parliament, with Mr Clegg holding the balance of power.
But Mr Dean, who was briefly frontrunner for the 2004 Democratic Party nomination and whose infamous "Iowa scream" - a yelp of defiance at a campaign rally - became an internet hit, said Mr Clegg believes he can win outright.
Speaking on the Washington Journal, simulcast on US network C-Span and BBC Parliament, he said: "I don't think there'll ever be a coalition between the Liberals and the Labour government.
"I know the Liberals, I know Nick Clegg very well, and he intends to win this and I think they could.
"So you may have a hung Parliament but I think you won't have a coalition. At least not that coalition going forward."
Asked if Mr Clegg could be the next British prime minister, Mr Dean said: "I think he could".
Mr Dean, who was chairman of the Democratic National Committee from 2005 to 2009, has close links with the Lib Dems and has spoken at their party conference in the past.
He acknowledged that Britain's electoral system mitigated against a Lib Dem victory in the general election, widely expected to take place on 6 May.
"It's a different system ours, first-past-the-post, but I think the debates are going to be enormously helpful to everybody. He is a young, dynamic leader that they don't know much about and the Brits really would like a change.
"Just the fact that Labour and the Conservatives are so close shows that the Conservatives are not what they want either.
"They're mad at Labour, they don't want the Conservatives, they happen to have a young dynamic leader, leading a party that in fact has been in power in Britain and run governments in Britain, although not for the past many decades, and I think those debates are going to put them all on an equal footing and I think Nick Clegg could make a lot of hay out of this."
Mr Clegg declared in his party conference speech last year that he wanted to be prime minister.
It was talked up by his aides as the most ambitious statement ever made by a Lib Dem leader, but it attracted ridicule from political opponents and some commentators.