With the second Democratic presidential primary debate out of the way and Congress about to head into a six-week summer recess, American politics is officially entering the doldrums.

Of course, in the age of Donald Trump, there are no true down times or dead air, but "traditionally, this is a really, really difficult period to get noticed," says Joe Trippi, a veteran Democratic strategist who led the 2004 presidential campaign of Howard Dean.

That's why for the 20 candidates vying to be the Democratic nominee for president in the 2020 election, the two nights of televised debate in Detroit this week were a crucial opportunity to make an impression, especially on those who will be voting in the party's caucuses and primaries early next year.

Which is not to say that they fundamentally altered the race. Former vice-president Joe Biden, having weathered attacks on his record on criminal justice and desegregation in Wednesday's debate, is still the front-runner despite an uneven performance.

WATCH | "You're dipping into the Kool-Aid': New Jersey Senator Cory Booker challenges Joe Biden on his past support of tough-on-crime laws:

New Jersey Sen. Cory Booker chastises former vice-president Joe Biden for passing tough-on-crime laws that destroyed African American communities. 2:01

Senators Elizabeth Warren and Bernie Sanders remain locked in a tug of war for the party's progressive wing, although the consensus was that Warren gained an edge in this round.

California Sen. Kamala Harris is likely to remain stuck in fourth place, having failed to top her June debate performance and taken hits from Hawaii Rep. Tulsi Gabbard Wednesday night over her own criminal justice record dating back to her time as a prosecutor and attorney general in California.

WATCH | Rep. Tulsi Gabbard accuses Sen. Kamala Harris of keeping inmates in prison longer than needed when she was a prosecutor in California:

Hawaii Rep. Tulsi Gabbard challenges California Sen. Kamala Harris on her prosecutorial record, saying she kept prisoners locked up longer than they needed to be. 2:08

The also-rans showed up, and some even stood out, but it remains to be seen how many will stay in the race.

As of Thursday, of the 16 candidates polling at six per cent or lower, only New Jersey Sen. Cory Booker, South Bend, Ind., Mayor Pete Buttigieg and former Texas congressman Beto O'Rourke had met the qualifying requirements for the next debate in September: 130,000 donors and four polls with support above two per cent.

Democrats likely to play it safe

Trippi said that while peripheral candidates like Julián Castro, who took a strong stance on decriminalizing illegal border crossings during Wednesday's debate, grab some attention — and maybe even a bump in the polls — in the debates by trumpeting a signature issue, interest in them generally fades as voters start finding flaws.

In an election where Democrats have placed a high value on electability and the ability to beat Donald Trump, even loyal supporters start to get gun shy about their candidate.

Senators Bernie Sanders, left, and Elizabeth Warren, centre, shared the debate stage on Tuesday but did not attack each other's proposals, many of which are similar. Former Texas congressman Beto O'Rourke, right, had a lacklustre performance but will move on to the next round of debates in September. (Justin Sullivan/Getty Images)

"I'm sure there are a lot of people out there saying, 'I still love Bernie ... but oh man, Democratic Socialist against Donald Trump? I just don't think I can take that chance,'" Trippi said.

"They all go home to Joe Biden."

Trippi suspects that for all the praise of Warren's energy and big ideas on the first night, in the face of a "chaotic, abrasive" Trump presidency, Democrats are ultimately seeking a moderating force.

"Biden, who they all claim doesn't excite anybody, has 51 per cent of the African-American vote, is leading among women and is second among young voters," he said. "I think what they're looking for really is somebody who is steady."

Even the hits he took from Harris and Booker Wednesday on his support for tough-on-crime laws in the 1980s and 90s, which disproportionately affected African Americans, likely won't impact that too much, Trippi said. The issue could cost him some young voters, but older African Americans who lived through the crack cocaine era that spurred the legislation have cut him more slack, he said.

"They understand the context of some of those votes or things he's done, and they may not agree with it, but they've kind of lived through it with him."

WATCH | Elizabeth Warren made bold statements Tuesday night, but can she take her candidacy through the long primary season?:

Massachusetts Senator Elizabeth Warren criticizes Rep. John Delaney for an agenda that is not ambitious enough for a presidential race in the second round of Democratic primary debates. 0:50

10 more debates to go

With 20 candidates spread over two nights, there were a lot of distractions on the debate stage in Detroit, says Tim Lim, a Democratic strategist and partner at Newco Strategies who worked on the Hillary Clinton campaign in the 2016 election.

September, at the third round of debates in Houston, is when the choice between candidates will start to crystallize in a more substantive way, he said.

"This is where you'll finally start seeing the differentiation, the long-term strategy, the long-term messaging."

Former housing secretary Julian Castro, left, and Washington Gov. Jay Inslee are far down in the polls and may not raise the funds or support they need to qualify for the Sept. 12 and Sept. 13 debates. (Scott Olson/Getty Images)

It's also when you might see some of the alliances that were on display in this round start to fray and candidates like Sanders and Warren, who advocate similar far-left policies on health care, education and taxes, emphasize their differences.

"It's just going to be really difficult for either of them to be the nominee unless one is sliding in the polls," Lim said.

Democrats have said they plan to hold 12 debates in the 2020 election cycle, including four more this year.

And eventually, one of the candidates will have to take on Trump, and tactics that worked in the primary debates might go out the window, said Aaron Kall, who runs the debate program at the University of Michigan and authored a book on Trump's 2016 election campaign debates called Debating the Donald.

Sanders's blunt, in-your-face style, for example, might not be as effective as it was Tuesday night.

"In a primary debate amongst mostly Democrat and many liberal voters, his style and, certainly, his policy positions work, but in a general election debate against President Trump, I'm not sure that you'd be able to pull that off," said Kall.

WATCH | 'I wrote the damn bill': Bernie Sanders defends his health care proposal in Night 1 of the debate:

U.S. Democratic presidential hopefuls Bernie Sanders and Tim Ryan debate whether 'Medicare for All' would improve health-care coverage for people who already have a plan through their employers or their unions. 1:33

Debates aren't everything

Success in debates doesn't necessarily translate into electoral wins, he said, which is good news for someone like O'Rourke, who has admitted it's not his strong suit and performed relatively poorly this week.

Unlike other moderate candidates, such as John Delaney and Tim Ryan, O'Rourke wasn't willing to mix it up with his progressive rivals on stage the first night.

"He's likely not going to ever make up ground on the debate stage, so it's not going to be a big part of his campaign," said Kall.

More substance, less posturing

One voter who was watching this week said she'd like to see less infighting and more talking about issues the next time around.

Ponsella Hardaway runs an interfaith organization in Detroit called Metropolitan Organizing Strategy Enabling Strength that helps communities across Michigan tackle practical problems in areas such as municipal water infrastructure, transportation, housing and health care.

Hardaway said that while candidates like Washington Gov. Jay Inslee and Booker came across as passionate and authentic in Wednesday's debate, the focus on attacking front-runner Biden took time away from thoughtful discussion of issues.

WATCH | New Jersey Sen. Cory Booker makes a plea for party unity:

New Jersey Sen. Cory Booker calls out Democrats for infighting, and for pitting progressive candidates against moderates. 'That to me is dividing our party,' and distracting from the real enemy, he said. 0:21

"They want to go after each other, not really the substantive things that we want to address given where we are in this country today," she said.

The need to shore up infrastructure and ensure access to safe and affordable water are two of the issues she'd like to see the candidates tackle, but she also liked the sound of tech entrepreneur Andrew Yang's proposal of a basic income of $1,000 a month.

"It's not trivial," she said. "I'm not looking necessarily for people to have welfare, but how do we get people on a path that they can come out of survival mode."

She sees it as something that could help not just the poor but also the middle class, to offset costs such as child care.

"I hope that's not dismissed. I hope that is something that's looked at very closely. People do need something to actually keep them afloat."

'We all are hurting'

On the second night of the debate, candidates were asked what they would do for Michigan, a battleground state Democrats narrowly lost to Trump in 2016 that will be key in the November 2020 election.

"They said Detroit was coming back, but they don't know the whole story of Detroit," Hardaway said. "People still don't have jobs. There's inequity in terms of how investment is coming back into certain cities."

Some of the candidates praised Detroit's recovery, but resident Ponsella Hardaway, executive director of the interfaith organization Metropolitan Organizing Strategy Enabling Strength, says many in the city still have trouble accessing basic services, such as water. (Michael Mathes/AFP/Getty Images)

Just because there is widespread disgruntlement with Trump doesn't mean Democrats should take Michigan's votes for granted, she said.

People in the cities, suburbs and rural areas she works in are still apprehensive of throwing in their lot with any one party, she said.

"Especially those in the conservative communities still have questions," she said. "I think people want to be able to talk about their own plight and not get pushed into a corner because they believe a certain way ... We all are hurting."