Democratic presidential hopefuls Hillary Clinton and Bernie Sanders will face off in their final debate before the crucial New York primary.
Mrs Clinton and Mr Sanders have ratcheted up their attacks in recent days, trading barbs about their qualifications for the presidency.
The Democrats have largely avoided the personal attacks that have dominated the Republicans’ debates.
But with so much at stake, Thursday’s debate could change that.
Mr Sanders has repeatedly criticised Mrs Clinton for her and her supporters’ financial ties to Wall Street and the fossil fuel industry.
Meanwhile, Mrs Clinton has questioned whether Mr Sanders has adequately thought out his policy proposals after he struggled to provide specifics during an interview with the New York Daily News.
Clinton v Sanders: Three key differences
Campaign finance: Mr Sanders has declined to make use of outside groups, commonly known as Super Pacs, to help support his campaign. Instead, the Sanders campaign has created an online fundraising operation that draws mostly from small donors. The Super Pac Priorities USA Action indirectly supports the Clinton campaign. Mrs Clinton also draws a significant amount of support from large individual donors. Mr Sanders maintains that Super Pacs and donations from people in certain industries like the financial sector have compromised the Clinton campaign. Mrs Clinton has fought back, denying that contributions affect her decision making and calling Mr Sanders’ accusations “an artful smear”.
Healthcare: Mr Sanders has advocated a single payer, government-run healthcare system like those found in European counties. Mrs Clinton believes that Democrats should build on the progress made by President Barack Obama’s healthcare reform law, which relies on privately run insurers and sharply decreased the number uninsured people in the US. Mrs Clinton says Mr Sanders’ plans are not realistic and would require large tax increases.
Foreign policy: A former secretary of state, Mrs Clinton has been a strong advocate of military intervention. She approved of the Iraq War in 2002 and supported overthrowing Libyan dictator Muammar Gaddafi. Mr Sanders has been harsh critic of the Iraq War and has been sceptical of interventionist policies. He argues that more resources should be devoted to domestic programmes. Mrs Clinton portrays herself as a realist who is the best prepared to deal with a dangerous world. She often attempts to paint Mr Sanders as out of his depth when it comes to foreign policy.
A resurgent Mr Sanders has won seven of the last eight contests, sparking a groundswell of enthusiasm from his supporters.
The Sanders campaign drew more than 25,000 people to a rally on Wednesday in Washington Square in Manhattan.
However, buoyed by earlier wins across the southern US, Mrs Clinton holds sizeable lead in the number delegates needed to secure the nomination.
Many analysts believe that Mr Sanders needs to pull off an upset in New York to remain viable in the race.
Mrs Clinton, who represented the state in US Senate for two terms, holds a commanding lead in New York, according to recent polls.