The race for the Democratic presidential nomination enters a new phase this week, with candidates desperate to make an impact in a second round of debates.

The debates, which take place on Tuesday and Wednesday evening in Detroit, offer a last chance for some candidates to break out of the lower tiers in the field.

Among the top candidates, the verbal punches will fly thick and fast as the big names vie for an advantage at the last big event before the campaign quietens down for much of August.

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“It’s going to be like Thunderdome,” said one Democratic strategist unaligned with any presidential candidate. “Ten come in, but who knows how many come out?”

Ten candidates will debate each night. The clashes will be televised by CNN.

Former Vice President Joe Biden Joe BidenPelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Hillicon Valley: Subpoenas for Facebook, Google and Twitter on the cards | Wray rebuffs mail-in voting conspiracies | Reps. raise mass surveillance concerns Fox News poll: Biden ahead of Trump in Nevada, Pennsylvania and Ohio MORE remains the front-runner in the race but is showing signs of weakness. Sens. Elizabeth Warren Elizabeth WarrenHillicon Valley: Subpoenas for Facebook, Google and Twitter on the cards | Wray rebuffs mail-in voting conspiracies | Reps. raise mass surveillance concerns On The Money: Anxious Democrats push for vote on COVID-19 aid | Pelosi, Mnuchin ready to restart talks | Weekly jobless claims increase | Senate treads close to shutdown deadline Democratic senators ask inspector general to investigate IRS use of location tracking service MORE (D-Mass.), Bernie Sanders Bernie SandersThe Hill's Campaign Report: Trump faces backlash after not committing to peaceful transition of power Bernie Sanders: 'This is an election between Donald Trump and democracy' The Hill's 12:30 Report: Trump stokes fears over November election outcome MORE (I-Vt.) and Kamala Harris Kamala HarrisHundreds of lawyers from nation's oldest African American sorority join effort to fight voter suppression Biden picks up endorsement from progressive climate group 350 Action 3 reasons why Biden is misreading the politics of court packing MORE (D-Calif.) are, for now, the three candidates best placed to supplant him.

This week’s debates will inevitably be seen through the lens of the first clashes, which took place a month ago in Miami.

Biden had a bad night in Magic City. Harris criticized him in forceful terms for his opposition to federally mandated school busing and for his sympathetic remarks about Southern segregationist senators of a previous era.

In the aftermath, the California senator rose sharply in the polls and Biden drifted down.

Biden has to do much better this time around, before anxiety among his supporters becomes a full-on panic.

Democratic strategist Julie Roginsky, asked if she still considers the former vice president to be the leading candidate, replied, “Today. But I don’t know how many more debate performances where he is not hitting it out of the park he can absorb.”

Biden aides have indicated that they will take a more aggressive line against attacks, however. The candidate himself seems to understand the stakes.

“I’m not going to be as polite this time,” he told supporters at a fundraiser Wednesday.

Biden supporters know he needs to show more fight this time — in part to bolster his central argument that he would be the most formidable candidate to face President Trump Donald John TrumpSteele Dossier sub-source was subject of FBI counterintelligence probe Pelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Trump 'no longer angry' at Romney because of Supreme Court stance MORE in November 2020.

Trump being Trump, he is sure to seize on any sign of weakness or hesitancy on Biden's part this week.

Several sources who spoke to The Hill also noted that Harris’s success after slamming Biden in Miami is certain to encourage other candidates to take a leaf out of the same book.

“Harris scored a lot of plaudits for the way she conducted herself last time — which opens the door for others to do the same,” said Roginsky.

The potential for controversy is especially high because Biden will be flanked on Wednesday by Harris and Sen. Cory Booker Cory Anthony Booker3 reasons why Biden is misreading the politics of court packing Bipartisan praise pours in after Ginsburg's death DHS opens probe into allegations at Georgia ICE facility MORE (D-N.J.), the two major African American candidates in the race.

In addition to the lingering Biden-Harris tensions, Booker and Biden have been increasingly willing to hit each other directly.

Booker raised the issue of Biden’s support for a controversial 1994 crime bill last week after the former vice president released his new plan for criminal justice reform.

“The proud architect of a failed system is not the right person to fix it,” Booker said in a statement.

The pointed jab drew an acerbic response from Team Biden.

Biden’s deputy campaign manager, Kate Bedingfield, accused Booker of making “specious charges” and said that he had “some hard questions to answer” about his own past positions on policing — including a "zero tolerance" approach Bedingfield said Booker supported while mayor of Newark, N.J.

Booker is among the candidates who has been struggling to gain traction in the race, despite having a high profile at its outset. It was only on Monday morning that his campaign announced he had reached the criteria to qualify for the third round of debates, to be held in September.

Six candidates had already done so. Biden, Sanders, Warren and Harris were joined by South Bend, Ind., Mayor Pete Buttigieg Pete ButtigiegBillionaire who donated to Trump in 2016 donates to Biden The Hill's Morning Report - Sponsored by Facebook - GOP closes ranks to fill SCOTUS vacancy by November Buttigieg stands in as Pence for Harris's debate practice MORE (D) and former Rep. Beto O’Rourke (D-Texas).

The much-hyped O’Rourke has also struggled to live up to expectations so far. His quest was further hindered by a mediocre debate performance in Miami when he came under attack from former Housing and Urban Development Secretary Julián Castro.

Booker, O’Rourke or any number of more marginal candidates could come out swinging on Tuesday or Wednesday.

But there is also the danger that such attacks could backfire.

“It depends where you’re at,” said Joe Trippi, who was former Vermont Gov. Howard Dean’s presidential campaign manager in 2004. “If you are at 1 percent in the polls, then unless you get attention, it’s all over. On the other hand, pouring gasoline around and lighting a match is not likely to work either.”

Still, this week’s debates are a do-or-die moment for some.

Given the stricter rules that govern admission to the September debates, “this will be the last time I think we will see a third to a half of this group,” predicted Mitchell McKinney, the director of the Political Communication Institute at the University of Missouri.

In Detroit, candidates will also have to grapple with the dynamics of whether to confine their barbs only to rivals who are on stage alongside them or to take aim at someone who is debating on another night.

Sanders and Warren are the two highest-polling candidates debating on Tuesday, raising the possibility that their clash could become a struggle for primacy among left-leaning voters.

But their presence together could also give Sen. Amy Klobuchar Amy Klobuchar3 reasons why Biden is misreading the politics of court packing Social media platforms put muscle into National Voter Registration Day Battle lines drawn on precedent in Supreme Court fight MORE (D-Minn.) a chance to contrast the Sanders-Warren agenda with her own, much more centrist platform.

The importance of the debates in Detroit could also be magnified because they come at a time when the flow of other political news is beginning to slow.

The House of Representatives is already in recess. The Senate has just one more week in session before its members are also expected to leave the Capitol.

That means the battlefield is clear for the Democratic presidential candidates to tangle directly with President Trump — or with each other.

“Get your popcorn,” advised Trippi. “There’ll be fireworks from somewhere.”

The Memo is a reported column by Niall Stanage, primarily focused on Donald Trump’s presidency.

This column was updated at 9:01 a.m. on July 29, after Sen. Cory Booker's campaign publicly announced he had reached the criteria for inclusion in the September debates.