Democratic debates: Who were the winners and losers?

The first Democratic debate double-header is in the books. Two nights, two groups of 10, one set of winners and losers.

Here's a look at who ended up on top this week and who was left stumbling for the exits.

The California senator had the most memorable line of the debates, when she jumped into a moment of cacophony on the second evening with a zinger that is sure to be on heavy rotation in the post-debate coverage: "America does not want a food fight, they want to know how we are going to put food on the table."

It was an example of the sharp timing Harris had all evening. She picked her moments and had tight, focused and often emotional answers. On the topic of healthcare, she told a story about a mother outside an emergency room, debating whether her child's fever was worth the expensive insurance payment she would incur for treatment.

On immigration, she spoke of refugee families journeying from Central America who were being denied asylum from the Trump administration.

"That is not reflective of our America and our values, and it's got to end," she said.

Then, in the second half of the debate - with all the momentum built up over a successful first hour - she put Biden to the sword. Turning to the vice-president, she told him it was "hurtful" to hear him speak of his warm relations with segregationist senators and for him to stand by his opposition to government-mandated school bussing.

The vice-president looked visibly shaken.

Facing down the front-runner was the coup de grace on a standout evening.

Like the Hippocratic Oath, Elizabeth Warren's first directive was to do no harm. She had the lighter of the two debate draws and so avoided most of the fireworks - which, given her steadily rising poll numbers, is exactly what she needed to do. Fireworks can be fun to watch, but it's easy to get burned.

If there are some storm clouds on the horizon for the Massachusetts senator, they could come from her early and eager endorsement of replacing private health insurance with a government-managed "Medicare for all" system. That may inoculate her from criticism by Bernie Sanders for being insufficiently progressive, but it will open her up for attacks from conservatives as being too extreme if she were to become the Democratic nominee.

Those are worries for another day, however.

As one of the multitude of candidates polling at or around 1%, Julian Castro had expectations that were low to non-existent. He easily surpassed them in the first debate, getting the better of Beto O'Rourke in an exchange on immigration, drawing applause for his call for policing reform and leaning heavily into his child-of-immigrants personal story.

Time will tell whether his moment in the limelight translates into anything more than fleeting glory - and, perhaps, a closer look from the eventual nominee for the vice-presidential slot.

It looked like everything was breaking the former vice-president's way in the second debate. He wasn't always sharp in his answers and had the tin-eared "I'm still holding the torch" line - which could be a new slogan for the Baby Boom generation. But he warmed up over time, as he often does these days. He seemed to hit his stride in an answer about immigration and the plight of "children in cages" at the border.

Then Kamala Harris struck. For the first time in the debate, the vice-president was on the defensive. For the first time, he looked vulnerable. Colorado Senator Michael Bennet followed up, turning a Biden boast about coming up with a bipartisan budget deal during the Obama administration into fault - pointing out that the deal extended Republican-passed tax cuts.

"It was a victory for the Republican Party," he said.

Biden can certainly recover from this debate. In fact, he probably will. But his campaign is built primarily on left-over good feelings from the Obama administration and the belief among many Democrats that he is the best candidate to beat Donald Trump. Thursday night's debate may leave some in the party wondering if he's going to be able to hold up over the course of a long campaign.

If the alarm bells aren't sounding in Beto O'Rourke's campaign, they should be. He's been sinking in the polls, and Wednesday night's debate performance is more likely to be an anchor than a lifeline.

While the former Texas congressman had the second most speaking time in the first debate, very few things he said were memorable. And his most notable exchanges were unfavourable ones.

New York Mayor Bill de Blasio pushed him around during the healthcare portion of the debate. He was also roughed up by Julian Castro - Julian Castro! - on immigration, which should have been O'Rourke's marquee issue.

Unless things turn around quickly for him, the suggestions that he should have stuck around Texas and run for Senate again instead of vying for the top prize are going to grow.

As fictional racecar driver Ricky Bobby might say, if you're not a debate winner, you're a debate loser. For all but maybe a half-dozen candidates in this 24-person field, the opportunities to emerge from relative obscurity and kick-start a moribund campaign are few and far between. This week's debates were one such moment.

If that moment passes by without a standout success - even if it was a debate showing with no stumbles, bumbles or gaffes - then the campaign clock takes one more stroke closer to midnight.

Bernie Sanders was Bernie Sanders. He had his lines, he had his well-practised pitches, he will keep his supporters in line. Pete Buttigieg gave a reasonable, though largely unmemorable, performance - but he has enough momentum to live to fight another day.

That next big day will come in the Detroit debates next month, but for many in the field that may well be the last chance to catch fire. There are no debates in August, and the bar for qualifying for the September gathering is decidedly higher.

It won't be long before some of the candidates who travelled to Miami start scanning the skies for circling vultures.