As Democrat presidential hopefuls prepare to face off in a second night of debates, all eyes are on former Vice-President Joe Biden, the party’s frontrunner.
He will be sharing a stage in Detroit with nine other Democrats, including California Senator Kamala Harris.
In their prior debate in June, Ms Harris aggressively attacked Mr Biden’s race relations record.
Mr Biden has vowed to fight back: “I’m not going to be as polite this time.”
The winner of the Democratic presidential nomination will be announced next July at the party convention.
The presidential election will take place months later, in November 2020.
What to watch out for
Much of the focus will be on Mr Biden, with polls showing him in the lead among Democrats. He is considered to be the moderate centrist of his party, with the best chance of wooing voters who supported Republican Donald Trump in the 2016 election.
But he had a difficult night in the debate last month in Miami, with Ms Harris attacking him over his record of opposing school desegregation via mandatory bussing back in the 1970s.
After the debate he saw a dip in the polls, while Ms Harris rose, and he will be looking to regain his momentum.
For many of the candidates, this could be the final opportunity to make their case in front of a national audience before the next debate in September, in which only 10 candidates will be allowed on stage.
Candidates will be very keen to see a rise in support and fundraising figures after the primetime spectacle.
Biden in the crosshairs again?
The June exchange between Mr Biden and Ms Harris was a one-sided affair, as he appeared caught off guard by her criticism, which culminated with her noting that she was a direct beneficiary of the kind of efforts then-Senator Biden opposed.
The encounter crystallised the consensus that the former vice-president had an uneven debate performance and helped give Ms Harris a noticeable boost in the polls (accompanied by a Biden dip).
Mr Biden has steadied himself since then, but there is blood in the water. He and Ms Harris once again share the stage in the Wednesday night debate, and Biden has said he’ll be ready this time.
He better be. The shots, however, may not come from Ms Harris, who has probably squeezed all the benefit she can from tussles with Biden.
Others on the stage – particularly Senators Cory Booker and Kirsten Gillibrand – may have taken note of Ms Harris’ success and seek to replicate it.
Right now a plurality of Democratic voters appear to think Mr Biden is the candidate best able to go toe-to-toe with Donald Trump in 2020.
He’ll have to prove he can handle his primary opponents first, however. He didn’t do that in the first debate in June.
He now has another opportunity, but falter again, and the whispers that he may not be the man for the job will grow louder.
Who will be on stage?
The line-up has been chosen at random by CNN, who are hosting the event.
In addition to Mr Biden and Ms Harris, the debaters will be:
- New Jersey Senator Cory Booker
- Former Secretary of Housing and Development Julián Castro
- New York City Mayor Bill de Blasio
- Hawaii Congresswoman Tulsi Gabbard
- New York Senator Kirsten Gillibrand
- Colorado Senator Michael Bennet
- Washington Governor Jay Inslee
- Business entrepreneur Andrew Yang
What happened in the first debate?
During Tuesday’s debate, Bernie Sanders and Elizabeth Warren – who represent the left-most wing of their party – defended their progressive policies against centrists.
Several candidates called the progressive senators’ policies – on issues such as healthcare and university tuition – unrealistic and not the best way for the party to defeat President Trump.
The politicians disagreed over whether to keep border crossings illegal, and whether reparations should be paid to black Americans for the crime of slavery.
But the 10 hopefuls largely agreed when it came to gun violence, dark money in politics and the need to urgently address climate change.
What’s the reaction been?
Mr Trump was quick to criticise the entire Democratic field, saying that without his 2016 victory, the US would be in an economic recession.
“The people I saw on stage last night, & you can add in Sleepy Joe, Harris, & the rest, will lead us into an economic sinkhole the likes of which we have never seen before,” he tweeted. “With me, only up!”
There has been criticism of CNN for the highly styled format of the debate.
It took nearly 25 minutes for the first questions to be asked, after CNN aired big budget trailers, paused for commercial break, and delivered lengthy opening statements.