03:55 - Source: CNN
How to win the presidential debate

Editor’s Note: Jen Psaki, a CNN political commentator, was the White House communications director and State Department spokeswoman during the Obama administration. She is vice president of communications and strategy at the Carnegie Endowment for International Peace. Follow her at @jrpsaki. The opinions expressed in this commentary are solely those of the author. Read more opinion articles at CNN.

CNN  — 

On Thursday, we will finally see the much-anticipated showdown between former Vice President Joe Biden and Senator Elizabeth Warren, when 10 Democratic candidates meet for a three-hour debate hosted by ABC.

The two have a decades-long history, dating back to Warren’s outspoken opposition to a Biden-backed bill intended to overhaul the US bankruptcy laws. Warren’s argument has long been that Biden sided with credit card companies and lenders to support legislation that would hurt low-income Americans, especially women.

Biden’s argument continues to be that the bill was going to pass with a Republican in the White House and he worked to make it better.

Beyond their policy differences, they both have something to prove. For Biden, it is that he can punch back for a three-hour debate and that his lead in the polls is not just about his bromance with former President Barack Obama.

For Warren, it is that she can take a punch directed at her personally from another Democrat on the debate stage, something she has not really had to contend with yet this cycle.

Warren has hinted that she will draw a contrast with Biden as the candidate who will fight for working people over the rich and powerful. Biden’s team have said they’re ready to take on the attacks that may come his way.

Biden vs. Warren may be the headliner that brings the curious political watchers from across the country to their couches to see what happens, but there are other dynamics to watch at the debate on Thursday:

The fight for who will emerge from the second tier

For the last few months, the top tier of Democratic candidates has looked pretty airtight. But each second-tier candidate is likely betting, and history supports this assumption, that there is room for another shift in the ranking before voting begins in February. And if anyone in the top tier falls, there is room for at least one other to jump on up.

Having delivered consistently solid debate performances at both the June and July debates, Pete Buttigieg and Senator Cory Booker are likely betting on picking up some of the support from the candidates who have recently dropped out of the race.

Senator Amy Klobuchar has been more inconsistent on the debate stage, but has hung in there with her message as the practical and more moderate Midwestern woman in the race. Julian Castro had a strong first debate, in part because he went after Beto O’Rourke on immigration, but didn’t see any lasting movement in the polls.

Will one of these candidates use the debate to position themselves as a top tier contender?

Sanders vs. Warren

At the CNN debate in July, Senator Bernie Sanders and Warren played nice on the debate stage instead of attacking each other. But that can’t continue forever. While Warren’s steady rise has pulled support from a number of candidates and given her reach with white college-educated voters, she has also pulled from the self-identified progressives who have long supported Sanders.

Sanders continues to have a high floor in the polls, but Warren has taken a big chunk out of his ceiling. Sanders has room to push the other candidates on Medicare for All, given he is the candidate who has given the most priority to a healthcare reform plan. Will he take a shot, even a gentle ribbing, at Warren, or hold his fire?

Harris v Harris:

There is no candidate who has benefited from a strong debate performance more than Senator Kamala Harris after the first debate. But it was short-lived. After a mediocre performance in the second debate and some criticism of her perceived flip-flopping on issues like Medicare for All, Harris could use a strong debate to help gain some momentum back.

This week she unveiled a criminal justice reform package aimed at addressing criticism from the left and reform advocates for her career as a prosecutor. She has effectively weaved between the Biden and Warren wings of the party, but that has also left an air of uncertainty around her own positions and points of view. Which Kamala Harris will come to the debate on Thursday?

The effect of the new O’Rourke strategy?

This isn’t a question of substance, but of style. At the first two debates, former Congressman and almost-Ted-Cruz-king-slayer Beto O’Rourke appeared uncomfortable, tired and light on substance. This was not the same Beto O’Rourke who went viral during his Senate run for giving a stirring answer to a question about kneeling during the national anthem.

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    Since the tragedy in El Paso, he has thrown out the playbook to focus much of his campaign energy on the issue of gun violence. There is no doubt that the topic will come up at the debate. Will he take advantage of that opportunity to recapture some of the magic of his Senate run?

    There are still three debates left planned for this year alone, but this is the last debate before the third quarter fund-raising deadline. Biden and Warren may be in the center ring, but there is plenty of action to watch for in the Democratic primary debate circus.