Former vice president Joe Biden and Sen. Kamala D. Harris (D-Calif.) participate in a Democratic presidential primary debate hosted by CNN in Detroit on July 31. (Paul Sancya/AP)
Opinion writer

For the third time, on Thursday, the Democratic candidates will come together for a debate. For the first time, they will all be on the same stage. The top-tier candidates have to hope that a mistake or misstep doesn’t slow or stop their momentum. Those in the second tier have to hope that a breakout moment will propel them (back) into the top tier.

But as the 10 candidates prepare for their big night, they have to be mindful that the Democratic faithful have made two things clear of late: 1.) They desperately want to electorally evict President Trump from the White House. 2.) They don’t like the Democrats fighting with each other on the debate stage, and they really don’t like what they think are cheap shots.

Point one was brought home last month in conversations at my family barbecue in North Carolina and at former vice president Joe Biden’s town hall that I attended in Rock Hill, S.C. Having plans and vision is great, but surefire applause lines involve tearing into Trump for the damage he has done the nation at home and abroad.

The impact of the second and more important point has taken a little while to manifest itself, but it has shaped the field. Placement on the debate stage is dictated by poll numbers, with the front-runner standing dead center and everyone else arrayed in descending order of support. Thus, the folks on the end and those looking for a breakout moment feel compelled to tap their inner “Hamilton” and do everything to not throw away their shot.

This is what Rep. Eric Swalwell (D-Calif.) did in the first debate when he went after Biden. “I was 6 years old when a presidential candidate came to the California Democratic convention and said it’s time to pass the torch to a new generation of Americans,” Swalwell said. “That candidate was then-senator Joe Biden. Joe Biden was right when he said it was time to pass the torch to a new generation of Americans 32 years ago. He’s still right today.” His frequent use of “pass the torch” in that debate earned him justified ridicule.

But it was Swalwell’s smack at South Bend, Ind., Mayor Pete Buttigieg (D) for not firing the police officer who shot and killed an African American man on June 16 that was most memorable.

BUTTIGIEG: I have to respond to that. We have taken so many steps toward police accountability that the FOP denounced me for too much accountability, and I accept responsibility for that because I’m in charge.

SWALWELL: If the camera wasn’t on and that was the policy, you should fire the chief.

BUTTIGIEG: So under Indiana law, this will be investigated, and there will be accountability for the officer involved.

SWALWELL: But you are the mayor. You should fire the chief — if that’s the policy and someone died.

It was a total cheap shot since Buttigieg had just explained why he legally couldn’t sack the cop. Yet, Swalwell persisted. The look from Buttigieg was withering. Twelve days later, Swalwell, who registered zero percent support in most polls and not more than one percent in a handful of surveys, became the first major candidate to end his presidential campaign.

Sen. Kirsten Gillibrand (D-N.Y) is a significant player in the Senate. Her entry into the Democratic nomination race was widely anticipated. That she didn’t rise to others’ expectations was surprising to many. That she wasn’t going to throw away her shot during the second night of the July debate to try to break out of the pack was not. The junior senator from New York used a 1981 op-ed by Biden, then a senator from Delaware, to accuse him of arguing that working mothers were destroying the American family.

GILLIBRAND: I want to address Vice President Biden directly. When the Senate was debating middle-class affordability for child care, he wrote an op-ed. He voted against it, the only vote, but what he wrote in an op-ed was that he believed that women working outside the home would, quote, “create the deterioration of family.” He also said that women who were working outside the home were, quote, “avoiding responsibility.”

And I just need to understand as a woman who’s worked my entire career as the primary wage earner, as the primary caregiver, in fact, the second — my second son, Henry, is here, and I had him when I was a member of Congress. So under Vice President Biden’s analysis, am I serving in Congress resulting in the deterioration of the family, because I had access to quality affordable day care? I just want to know what he meant when he said that.

BIDEN: That was a long time ago, and here’s what it was about. It would have given people making today $100,000 a year a tax break for childcare. I did not want that. I wanted the childcare to go to people making less than $100,000. And that’s what it was about. As a single father who in fact raised three children for five years by myself, I have some idea what it cost. I support making sure that every single solitary person needing childcare get an $8,000 tax credit now. That would put 700,000 women back to work, increase the GDP by almost 8/10 of 1 percent. It's the right thing to do if we can give tax breaks to corporations for these things, why can't we do it this way?

GILLIBRAND: But Mr. Vice President, you didn't answer my question. What did you mean when you said when a woman works outside the home it's resulting in quote, the deterioration of family ...

BIDEN: No, what I ...

GILLIBRAND: And that we are voiding — these are quotes. It was the title of the op-ed and that just causes concern for me because we know America’s women are working. 4 out of 10 moms have to work. They’re the primary or sole wagers. They actually have to put food on the table. 8 out of 10 moms are working today. Most women have to work to provide for their kids. Many women want to be working to provide for their communities and to help people.

DANA BASH: Thank you, Senator. Let the vice president respond now, thank you.

GILLIBRAND: So either you don’t believe it today or what did you mean when you said it then?

If you actually read the Biden op-ed, as I wrote after that debate, you see that the argument about the deterioration of the family had nothing to do with “allowing more women to work” and everything to do with the rich gaining on the backs of working families. Biden then, as he did at the July debate, was bemoaning a child-care tax credit that was being made available to upper-income Americans. Biden wrote about how he tried to make them ineligible and why.

Gillibrand was bouncing between zero and one percent support in the polls at the time of the July 31 debate and continued to do so in many surveys after. Exactly four weeks later, she ended her presidential campaign.

Sen. Kamala D. Harris (D-Calif.) was considered top-tier with Biden, Sen. Bernie Sanders (I-Vt.) and Sen. Elizabeth Warren (D-Mass.) when the first of the two-night debates took place in late June. In the lead-up to the debate, depending on the poll, Harris’s support was between five percent and seven percent. Harris scored her first breakout moment on the second night when she admonished her bickering fellow candidates, “Hey, guys, you know what? America does not want to witness a food fight, they want to know how we are going to put food on their table.” In the second hour of the debate, Harris took her shot.

And I’m going to now direct this at Vice President Biden, I do not believe you are a racist, and I agree with you when you commit yourself to the importance of finding common ground.

But I also believe, and it’s personal — and I was actually very — it was hurtful to hear you talk about the reputations of two United States senators who built their reputations and career on the segregation of race in this country. And it was not only that, but you also worked with them to oppose busing.

And, you know, there was a little girl in California who was part of the second class to integrate her public schools, and she was bused to school every day. And that little girl was me.

The folks at The Fix were kind enough to annotate the intense exchange. But the initial remarks highlighted above were a devastating knock against Biden that in the short term was enormously beneficial. The Harris campaign announced that it raised more than $2 million in the 24 hours after the debate. Her poll numbers popped up in most polls, hitting 20 percent in the Quinnipiac University poll released days after the debate compared with seven percent in the same poll earlier in June. Harris was either tied with Biden in the top spot or tied with Warren and/or Sanders in the No. 2 slot. But we can now see that that was a sugar high.

Sure, many factors play into a campaign’s poll numbers coming back to earth. And two from that first debate stand out. Harris’s attack on Biden for opposing court-ordered busing in the 1970s got muddled as she answered questions about what she would do today. So, her gambit in retrospect came off as canned and disingenuous. Her campaign’s decision to sell “That little girl was me” T-shirts hours after a rhetorical punch being thrown was seen as a little too planned and calculating by some of her supporters. Harris’s poll numbers have dropped ever since. By the time she took the debate stage on July 31, where she went on the attack against Biden again, her support was back down to around 10 percent.

Paradoxically, Harris has also been hobbled by the perception that she can’t take a punch. When Rep. Tulsi Gabbard (D-Hawaii) took her shot at Harris over her criminal-justice record as attorney general of California, many thought she was defensive and unprepared for the attack, which feeds into the just-below-the-surface concern that she can’t take on Trump.

It’s a mistaken concern for a proud woman from Oakland, Calif., who took off her earrings before a heated phone call with JPMorgan Chase chairman and CEO Jamie Dimon during negotiations in 2011 to settle the mortgage banking crisis. Nevertheless, Harris’s poll numbers dropped. The Quinnipiac University poll released before the July debate put her support at 12 percent. It dropped to seven percent in the Q poll released after that debate. That’s where it remains in the latest Post-ABC News poll.

That Gabbard punch was a no-win for Harris. Rank-and-file Democrats don’t want the candidates to attack each other, but they do want them to defend themselves when the punch comes. Yet for Harris, entertaining the attack by punching down and giving more airtime to a campaign gasping at one percent was perhaps a long-term strategic tactic that has hurt her in the short term.

The second pair of debate nights in July with its WWE atmospherics was the worst because the questions were designed to provoke fights, not engage in substantive discussions about the nation’s problems. Compounding the problem was that most of the candidates took the bait. When the 10 candidates who qualified for the next debate take the stage in Houston on Sept. 12, they should take every question designed to get them to attack an opponent and turn it into an opportunity to focus on the disaster that is the Trump presidency.

If the candidates do that, they will show primary voters that they can take the fight to an unfit president they want out of office. In a field still overflowing with options, they will avoid giving said voters a reason to go elsewhere. And, right now, the latest polls show they are going to Warren.

Follow Jonathan on Twitter: @Capehartj. Subscribe to Cape Up, Jonathan Capehart’s weekly podcast

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