The showdown in Brooklyn came at a pivotal moment in the party’s primary campaign, with Mrs Clinton leading in the delegate count but Sanders generating huge enthusiasm for his surprising candidacy. Mrs Clinton has accumulated 1,289 pledged delegates from primaries and caucuses while Sanders has 1,038. Her lead grows significantly when the superdelegates are added in: 1,758 for Mrs Clinton and 1,069 for Sanders.
It takes 2,383 to clinch the Democratic nomination. Mr Sanders would need to win 68 per cent of the remaining delegates and uncommitted superdelegates to reach that figure.
The Vermont senator took a biting and often sarcastic tone as he sought to chip away at Mrs Clinton’s credibility. He cited her support for the unpopular Iraq war and for free trade agreements, as well as her willingness to accept money through a super political action committee, as evidence that she lacks the needed judgment to lead the nation.
Still, Mr Sanders backed away from previous statements questioning Mrs Clinton’s qualifications, saying the former secretary of state does have the “experience and intelligence” to be president.
Mrs Clinton made little effort to hide her irritation with Mr Sanders’ challenging of her qualifications, saying that while she has been “called a lot of things in my life, that was a first”. She also cast Mr Sanders as unprepared to implement even his signature policy proposals, including breaking up big banks.
“I think you need to have the judgment on day one to be commander in chief,” she said.
The debate was the first for the Democratic candidates in five weeks. It came ahead of Tuesday’s primary in New York, a high-stakes contest.
For Mrs Clinton, a win in her adopted home state would blunt Mr Sanders’ recent momentum and put his pursuit of the nomination further out of reach. A Sanders upset over Clinton would shake up the race, raising fresh concerns about her candidacy and breathing new life into the Vermont senator’s campaign.
On the Republican side, Republican front-runner Donald Trump delivered an impassioned defence of the city he calls home. The billionaire businessman praised the city’s response to the nation’s deadliest terrorist attacks in remarks designed to jab leading rival Ted Cruz, a Texas senator who has repeatedly condemned “New York values” in his push to defeat the New York real estate mogul.
Mr Trump was the target of rowdy protesters who hung an effigy of the billionaire businessman and chanted, “How do you spell racist? T-R-U-M-P.” The scene came shortly after Florida prosecutors dismissed a criminal complaint against Mr Trump’s campaign manager, Corey Lewandowski, two weeks after he was charged with grabbing a reporter.
The Democratic primary has been fought on familiar terrain. Clinton has cast Sanders’ proposals for breaking up banks and offering free tuition at public colleges and universities as unrealistic. Sanders has accused Clinton of being part of a rigged economic and political system.