NEW YORK (AFP) - Hillary Clinton and Bernie Sanders take their increasingly acrimonious battle to win the Democratic nomination for the White House to the debate stage Thursday ahead of the key New York primary, as the Vermont senator disavowed a remark made by a speaker ahead of a huge Manhattan rally.
On Thursday Sanders disavowed a remark from healthcare activist Dr Paul Song, who railed against "corporate Democratic whores" at his rally the night before, in reference to politicians who - like Clinton - back more incremental healthcare reforms.
Sanders tweeted that the language was "inappropriate and insensitive" after Clinton's communications director Jennifer Palmieri demanded he do so, calling it "very distressing language."
Song, who is married to CNN journalist Lisa Ling, later apologised for being "insensitive" in referring to "some in Congress who are beholden to corporations and not us".
In recent days, Sanders, whose call for a revolution has ignited a passionate youth following, has questioned Clinton's judgment and called her remarks about young voters "a little bit condescending."
The former secretary of state holds a double-digit lead over Sanders in the New York polls and needs a big win in next Tuesday's primary after losing seven of the last eight contests to her leftist rival.
The Brooklyn-born Sanders, who calls himself a democratic socialist, is similarly dreaming of a shock win in Clinton's adopted home state to keep alive his dream of wresting the nomination from the Democratic frontrunner.
It makes for a dramatic showdown on the debate stage in Brooklyn, the borough where Sanders was born and raised, and which Clinton has made her national campaign headquarters.
Addressing what his team said was a crowd of 27,000 at the rally where Song made the controversial remark on Wednesday, Sanders attacked Clinton for her ties to Wall Street, her support for trade deals that have cost US jobs and for the 2003 Iraq invasion.
"This is going to be a tough primary for us but when I look at the thousands of people who are here... I think that if we have a large voter turnout on Tuesday we're going to win this state," he told the giant rally in Washington Square.
Clinton meanwhile is likely to drill Sanders on specifics about how he could enact his promise of political revolution after accusing him of being unable to give straight answers.
"I think it will be lively," she predicted of the debate, their first since March 9 and scheduled at Sanders' insistence as he looks to close his trailing gap behind the former first lady.
The two campaigns have traded increasingly heated blows in recent days.
Clinton has lashed out at Sanders over gun control and immigration reform. A video recently emerged of her snapping impatiently at an activist who accused her of accepting money from the fossil fuel industry.
"I'm so sick of the Sanders' campaign lying about me. I'm sick of it," she said.
Thursday's debate, to be moderated by CNN, kicks off at 9:00 am Friday Singapore time at the Duggal Greenhouse, a fashionable venue that has hosted events for the likes of Alexander Wang and Lady Gaga.
Clinton has a commanding advantage over Sanders with 1,790 delegates to his 1,113. A total of 2,383 delegates are needed to secure the party's nomination for the presidency in the party's convention this summer.
There are 247 Democratic delegates up for grabs in the New York primary, where minorities and wealthy Democrats are likely to favour Clinton, although polls suggest that Sanders has cut into her lead among white males and young voters. The state also attributes 44 superdelegates.
But the rules of the New York vote, in which only registered Democrats can take part, are likely to favor Clinton. Sanders has performed best in primaries that are open to independent voters.
The upshot is that New York, an overwhelmingly Democrat state whose primaries traditionally have little influence on presidential elections, may play its most decisive role in decades.
With Republican frontrunner Donald Trump potentially facing a contested nomination and Clinton a tighter national race than she would have liked, the votes on both sides could prove decisive.
Trump, the Manhattan tycoon, leads among New York Republican voters by 55 per cent to Ohio Governor John Kasich's 20 per cent. Texas Senator Ted Cruz, who was roundly condemned for denigrating what he called "New York values", has 19 per cent, according to a recent Quinnipiac University poll.
While the Democrats debate, the Republican candidates will be guests at a Republican gala at a posh Manhattan hotel.