Media playback is unsupported on your device Media caption What to look for in Thursday night's Democratic debate

The moment everyone - or at least someone, somewhere - has been waiting for has finally arrived. The Democrats will hold a single debate on Thursday with the top 10 candidates (by the Democratic Party's standards) all on the stage together.

At last, we can see how the front-runner, or runners, or almost-front-runners match up in locational and temporal proximity.

Here are five things to keep in mind when watching.

(Oh, and if you're pining for all those double-header debates, fear not. At least 11 candidates have qualified for October's debate, so it'll probably be back to two nights one more time.)

Elizabeth Warren in the limelight

During the first two double-header debates, Elizabeth Warren was always slotted in the first night, mostly surrounded by lower-polling candidates. While her performances garnered favourable reviews, they were always with the asterisk that her biggest potential foil - former Vice-President Joe Biden - was absent.

This time, they get to go head-to-head - and from early indications, both sides are girding for battle.

Biden's camp is indicating it could target Warren's past consulting for corporate clients as evidence that she's not as ethically pure as she makes herself out to be. He could also try to paint her "I've got a plan for that" progressive policy prescriptions as unattainable and off-putting to swing-state voters.

Image copyright Getty Images Image caption Elizabeth Warren and Joe Biden will square off for the first time at a debate

Warren won't have to reach as far back to unearth Biden's corporate ties. He's raised campaign funds from finance and energy companies and executives - a big no-no for some Democratic voters. Another strategy may be to try to dent Biden's veneer of electability, which has buoyed the former vice-president in the polls.

What's more, the two top candidates have a history of scuffling. A Youtube clip of then-Senator Biden and then-Professor Warren debating proposed financial reform back in 2005 has recently got viral attention.

At the time, Biden - with the backing of Delaware-based banking interests - was pushing for legislation that would make filing for personal bankruptcy more difficult. Warren, who made bankruptcy law her academic specialty, pushed back, calling existing bankruptcy laws "the last shred of protection" for financially pressed families.

She also wrote a New York Times opinion piece in 2002 suggesting Biden was in the pocket of the financial industry - a charge she made directly in April, when she said Biden was "on the side of the credit card companies".

Thursday's debate moderators will almost certainly try to rekindle some of that conflict. It shouldn't be too difficult, given that Biden is positioning himself as the steady, electable choice, while Warren is running on what she describes as big, structural change.

"You gave me hell," then Vice-President Biden told Warren when he swore her in as senator in 2013, possibly referencing the bankruptcy bill fight.

There may be more hell to come.

Biden under the microscope

Speaking of the former vice-president, his past two debate performances haven't exactly gone off without a hitch.

He stumbled through the first contest in Miami, getting noticeably rattled by California Senator Kamala Harris's swipes on racial issues. He frequently seemed a half step behind the other candidates - and even supporters worried he was showing all of his 76 years of age.

In the Detroit debate he offered a steadier performance, despite being surrounded by a pack of candidates out for blood. Muddled exchanges with Harris on healthcare policy and a bungled recitation of his campaign's text-message sign-up, however, kept him from putting concerns totally to bed. A series of gaffes and misstatements on the campaign trail haven't helped, either.

Image copyright Alex Wroblewski/Getty Images Image caption Biden campaigns in Iowa

Perhaps the third debate will be the charm, and he'll show his early struggles were just a veteran candidate shaking off the rust. His polling lead has proven fairly durable up to now, so even an adequate performance should do the trick.

Another clunker like Miami, however, and watch out for circling vultures.

The Bernie-Warren non-aggression pact

One of the big storylines going into the second round of debates in Detroit was that Warren and Vermont Senator Bernie Sanders would share the stage for the first time. It was breathlessly billed as a cage-match for progressive heart and minds.

Instead, it was a love-fest. The two grass-roots liberal icons took turns swatting away criticisms from moderate lower-tier candidates like former congressman John Delaney and Senator Michael Bennet. While supporters for Sanders and Warren may be eying each other nervously, there seems little appetite for conflict between the two principals - at least for now.

Image copyright BRENDAN SMIALOWSKI/Getty Images Image caption Sanders and Warren enjoyed a 'love-fest' at the July debate in Detroit

Could that change when both of them are facing debate jabs from Biden, a pugnacious Harris and an array of lean-and-hungry candidates, instead of 1% electoral also-rans?

For the moment, the dynamic progressive duo seems to be profiting from their alliance. Both are drafting behind Biden, comfortably ahead of the rest of the pack. While Sanders hasn't shown much movement in the polls, he has a steady base of support and a nationwide, grass-roots-fuelled campaign. Warren has a similarly strong operation and momentum on her side.

Warren and Sanders may be in for a bumpy ride on Thursday night as two of the top candidates on the stage, but chances are they'll keep watching each other's backs.

Harris's summer slump

After the first debate, it appeared Kamala Harris's moment had arrived. The California senator was sharp, both in her handling of questions and her move, at the midpoint of the evening, to go on the attack against Biden.

Her subsequent surge in the poll seemed to confirm the perception that she was the clear winner in Miami. On paper she had all the ingredients of a top-tier contender - a telegenic candidate from a diverse background with lots of money in the bank and the ability to appeal to both moderates and progressives. The consensus formed that these strengths were finally translating into tangible success.

Image copyright Justin Sullivan/Getty Images Image caption Kamala Harris speaks with voters in Iowa

Since then, however, she's dropped back to where she was before Miami. Her showing in the second debate was lacklustre, as she struggled to explain her shifting views on healthcare reform and defend her record as a California prosecutor and attorney general.

In an internal briefing memo accidentally left in a New Hampshire restaurant, her campaign referenced her "summer slump". Although the document did not offer much in the way of solutions, the most effective means of turning the tide is the path Harris has followed once before - to offer a debate performance that makes Democratic voters view her as the best equipped to go toe-to-toe with Donald Trump.

She won't have as big a target on her back as she did the last time around - and expectations will be somewhat lower - so it's not an unreachable goal.

Back of the pack

It seems strange to say, but with under five months left before Iowa's first-in-the-nation caucuses, time could be running short for many of the candidates on the stage Thursday night.

While it will only take Canadians about a month to conduct an entire election campaign, the US presidential hopefuls have been pretty much at it since the beginning of the year. Some - like Sanders and Biden - started near the top and have stayed there. Others - Warren and, for at least a while, Harris and Pete Buttigieg - have climbed their way up.

Media playback is unsupported on your device Media caption The best one-liners from the Democratic debate

The rest have either been spinning their wheels and making little headway or, in Beto O'Rourke's case, slowly sinking toward the bottom. Well-received debate performances from candidates like Senator Cory Booker, former Housing Secretary Julian Castro and businessman Andrew Yang haven't appeared to make much difference. Months of campaigning in key primary states is having little impact.

It could be that Democratic voters aren't buying what the Amy Klobuchars of the race are selling. Or perhaps they're just not paying attention - or are perfectly satisfied with what they're seeing from front-runners like Biden, Warren and Sanders.

Whatever the reason, the current dynamic needs to change for them to have a chance - and the sooner the better.

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