[PHILADELPHIA] Hillary Clinton made history on Tuesday by becoming the first woman to win a major US political party's White House nomination, earning the backing of convention Democrats and prime-time praise from a presidential superstar: her husband Bill.

The 68-year-old former first lady, senator and secretary of state took a monumental step on her quest to become America's first female commander-in-chief, by besting party challenger Bernie Sanders.

After a tumultuous convention opening which saw Sanders and Clinton supporters trade jeers and chants, cheers erupted as Mrs Clinton passed the 2,382-delegate threshold needed for the nomination, setting up a showdown with Republican Donald Trump in November.

Hours later, another historical moment greeted the Clintons, when a former president took the stage to intimately make the case that his wife was the compassionate and capable "change-maker" America needed.

"She always wants to move the ball forward. That is just who she is," Bill Clinton said of his candidate wife, keeping his audience of thousands of delegates rapt throughout his 45-minute speech, which marks the convention's halfway point.

"For this time, Hillary is uniquely qualified to seize the opportunities and reduce the risks we face, and she is still the best darn change-maker I have ever known." Although the roll call outcome was a foregone conclusion, the state-by-state vote saw rowdy displays on the convention floor.

A handful of diehard Sanders delegates fumed over their candidate's defeat, but they were drowned out by ecstatic Clinton supporters. Several wept and embraced.

Mr Sanders took the floor in a bid to unify the party, drawing deafening cheers and a chorus of "ayes" when he called for Mrs Clinton to be "selected as the nominee of the Democratic Party for president of the United States."

Delegates thrust placards in the air, forming a mosaic of "H's" across the arena.

Hillary Clinton made a stunning appearance by video after her husband's speech, appearing to burst through a symbolic glass ceiling comprised of the faces of former presidents, all men.

"What an incredible honour that you have given me," she said to roars from the crowd.

"This is really your victory," she added. "And if there are any little girls out there who stayed up late to watch, let me just say, I may become the first woman president but one of you is next."

Bill Clinton, a Democratic icon at 69, meanwhile reminded the audience why he is still considered such a spellbinding speaker.

While he made a forceful case for Hillary as president, his speech was deeply personal and heartfelt, taking his audience back to his earliest moments with his wife of more than 40 years.

"In the spring of 1971, I met a girl," Bill began as he warmly recalled their budding romance, his persistence in seeking her hand in marriage, and his eventual realisation that he was "in awe" at Hillary's smarts, strength and persistence in doing public good.

He alluded to Mrs Clinton's election rival, although not by name, by pointing to some of Trump's more controversial policy positions, including his call to ban Muslims from entering the United States.

"If you're a Muslim and you love America and freedom and you hate terror, stay here and help us win and make a future together," Mr Clinton said to huge applause.

"We want you." The Democratic convention has been convulsed by revelations over leaked Democratic National Committee emails that showed party bias against Sanders. Frustration boiled over on the opening day Monday as his delegates booed speakers who mentioned Clinton.

Mr Trump took the usual shots at Clinton during a speech in Charlotte, North Carolina, calling her "Crooked Hillary" and charging that her use of a private email account as secretary of state "put America's entire national security at risk."

But Bill Clinton took a veiled swipe at Mr Trump and his vision for change, and congratulated Democratic delegates for nominating "the real" Hillary, not the "cartoon" version portrayed by Republicans.

"Life in the real world is complicated, and real change is hard," Mr Clinton said.

"Today, you nominated the real one."

Tuesday's convention events drew sharp contrast with Mr Trump, with several speakers discussing Mrs Clinton's life-long fights to make a difference.

Several mothers of African-Americans who were victims of gun violence or police-involved deaths took the stage to back Mrs Clinton, as delegates chanted "Black lives matter."

Speakers also addressed the differences between Mrs Clinton and Mr Trump on women's rights, including Cecile Richards, the head of women's health care provider Planned Parenthood.

"Women are going to be the reason you're not elected president," Ms Richards said of Mr Trump.

Bill Clinton's speech struck a unifying tone. But despite Mr Sanders calling on his flock to get behind Hillary, his self-styled "political revolution" appears to have transformed into a revolt.

Tace Geesaman, a Nevada delegate and single mom, walked out after Mr Sanders's plea feeling betrayed.

"There's no unity in the party," she said of the Clinton camp.

"They're talking at us, they're telling us to fall in line," she added. "We didn't come to this convention to just fall in line."

But Bill Clinton laid out the options before voters, saying there were "clear, achievable, affordable" Democratic goals at stake in November.

"That's why you should elect her because she'll never quit when the going gets tough," Bill said of Hillary. "She'll never quit on you."

AFP