Miami, Jun 27 (AFP) Ten Democrats stepped into the national spotlight Wednesday kicking off their party's first debate of the 2020 presidential race, as Elizabeth Warren took centre stage to argue that her progressive policies can defeat incumbent Donald Trump.

The biggest American political debate since the 2016 presidential campaign is occurring over two nights in Miami, climaxing Thursday with former vice president Joe Biden squaring off against nine challengers, including number two candidate Bernie Sanders.

Despite the feverish political climate in Washington and heavy campaigning in early voting states, millions of Americans were tuning in to the 2020 race for the first time, eager to hear from some candidates who are only now introducing themselves to a national audience.

What they heard right off the bat was Warren knocking what she has routinely called a rigged economy, and quick clashes between candidates on issues like health care.

"Who's this economy really working for?" asked Warren, who received the first question.

"When you've got a government, when you have an economy that does great for those with money and is not doing great for everyone else, that is corruption, pure and simple," the US senator and former Harvard law professor added. "We need to call it out."

Candidates will have less than 10 minutes on average to make their mark, but each will want to walk off stage with a victory, perhaps a viral moment that advances their cause, draws new donors and keeps them in the headlines.

Wednesday's showdown, airing on NBC, is Warren's to lose. As the night's highest-polling candidate, she aims to build on the momentum that has propelled her campaign into the top tier.

But with four of the top five candidates debating on Thursday, Warren's session feels more like an undercard to the following night's main event.

She squares off against fellow senators Cory Booker and Amy Klobuchar, ex-congressman Beto O'Rourke, New York Mayor Bill de Blasio, Washington Governor Jay Inslee, and San Antonio ex-mayor Julian Castro, the only Latino in the race.

More than any other candidate, Warren, 70, has given a clear picture of her presidential priorities, like instituting a wealth tax, breaking up big tech companies and securing the US election system.

Trump was an obvious target during the showdown, and it will be telling to see how much Wednesday's debaters scuffle with one another, or collectively train their anger on the president, whom many of the candidates have said should face impeachment proceedings.

Moderators began by asking Democrats questions on the economy and rising US wealth inequality, and health care, and were expected to also address climate change, gun violence and Washington's showdown with Iran.

But the backdrop to the debate is the mushrooming crisis on the US-Mexico border, where the detention of migrant children in squalid conditions -- and a shocking photograph of a Salvadoran man and his baby daughter drowned in the Rio Grande -- has fuelled alarm and anger.

O'Rourke and Booker notably slipped into Spanish as they addressed the migration crisis -- and lashed out at Trump's record.

Candidates parried questions at a rapid pace, including de Blasio, who paused to remind viewers -- and his rivals -- that "this Democratic Party has to be strong and bold and progressive."

Booker, 50, an accomplished orator and African-American senator, is spinning his wheels in polling and needs a breakout moment to alter his trajectory in a very crowded field.

And O'Rourke, 46 and accused of having a thin resume, will try to show he has the policy chops, and not just the telegenic smile and energy that marked the early months of his campaign.

Many Americans will be watching more carefully Thursday when a clash of the old guard featuring Biden, 76, and Sanders, 77, might dominate.

The pair will face up-and-comers like Senator Kamala Harris, the only black woman in the race; Pete Buttigieg, the 37-year-old gay mayor of South Bend, Indiana; and dark horse Andrew Yang, an entrepreneur and political novice.

Despite flying to Asia Wednesday, Trump -- who has mocked Warren as "Pocahontas" for her claims of Native American heritage -- said he would tune in from Air Force One, and did not miss the chance to knock his would-be opponents via Twitter.

His verdict as the evening got underway? "BORING!" (AFP)

(This is an unedited and auto-generated story from Syndicated News feed, LatestLY Staff may not have modified or edited the content body)