Hillary Clinton and Bernie Sanders have clashed over Wall Street and foreign policy, in the Democratic presidential candidates' first one-on-one debate.

Mrs Clinton cast him as an idealist who will not get things done and Mr Sanders accused her of being too tied to the establishment to achieve real change.

The TV debate in New Hampshire was their first since the Democratic race was whittled down to two this week.

Without a third person on stage, the policy differences were laid bare.

The former secretary of state said Bernie Sanders' proposals such as universal healthcare were too costly and unachievable.

Democratic debate - as it happened

And she went after her rival aggressively over his attempts to portray her as being in the pocket of Wall Street because of the campaign donations and the fees she had received for after-dinner speeches.

"It's time to end the very artful smear that you and your campaign have been carrying out," she said.

Mr Sanders, a senator of Vermont, used a favourite attack line against her, that she backed the Iraq War, but she questioned his foreign policy expertise.

The debate comes five days before the second state-by-state contest in the battle for the presidential nominee, in New Hampshire on Tuesday.

Democratic debate: Winners and losers

Despite the tensions over policies, the debate ended on a warm note, when Mrs Clinton said the first person she would call would be Mr Sanders, if she won the nomination.

The debate was their first without the presence of the former governor of Maryland, Martin O'Malley, who quit the race on Monday night.

He was a distant third in the first state to vote, Iowa, where Mrs Clinton narrowly beat Mr Sanders after a prolonged count.

Mr Sanders holds a big lead in polls in New Hampshire, which borders the state where he is a senator, Vermont.

Both Republican and Democratic parties will formally name their presidential candidates at conventions in July.

Americans will finally go to the polls to choose the new occupant of the White House in November.

The winner of the Democratic contest will likely face one of Ted Cruz, Donald Trump or Marco Rubio, who finished in that order in the Iowa primaries.

Other highlights include:

She represents the establishment, I represent ordinary Americans, said Mr Sanders

By standing up to big money interests and campaign contributors, we transform America, he said

Mrs Clinton: "I am a progressive who gets things done, and the root of that word progressive is progress"

"Senator Sanders is the only person who would characterise me, a woman running to be the first woman president, as exemplifying the establishment", she added.

Mrs Clinton was asked to release the transcripts of all her paid speeches - she said she would look at it

He demanded the break-up of the big banks but she said her regulatory policies would be tougher on Wall Street

Asked what she stood for, she named clean energy, the affordable care act and getting paid family leave

He said he was stronger because "Democrats win when there is large turnout" and he could enthuse young people