Democratic primary voters have lower expectations for Joe Biden and Bernie Sanders' next debate performance, but higher expectations for Kamala Harris

• The next round of Democratic primary debates will take place on July 30 and 31 - and Democratic primary voters continue to have high expectations for how the frontrunners of the field will perform.

• INSIDER conducted a SurveyMonkey National Audience poll asking likely Democratic primary voters to pick up to five candidates who they expected would do the best in upcoming debates.

• Compared to the first round of polling before the June debates, fewer Democratic primary voters included former Vice President Joe Biden and Sen. Bernie Sanders among the candidates they expected to perform well, while more counted Sen. Kamala Harris in that category.

• Biden came into the June debates as the clear frontrunner, leading every single pre-primary poll. But Harris took control over the debate and knocked Biden back on his heels with sharp criticism over his record on race.

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The next round of Democratic primary debates will take place on July 30 and 31 - and Democratic primary voters continue to have high expectations for how the frontrunners of the field will perform.

Both before the first session of Democratic primary debates on June 26 and 27 and between July 19-20, INSIDER conducted a SurveyMonkey National Audience poll asking American adults who identified themselves as likely Democratic primary voters to pick up to five candidates who they expected would do the best in upcoming debates.

In all, 20 Democratic candidates have qualified to take to the stage in Detroit, Michigan, and will be evenly split between the two nights. In order to make the stage, candidates had to reach 1% in three DNC-approved polls and/or earn 65,000 unique donors.

Read more: Here's who will be on stage each night for the Democratic debates hosted by CNN, what time they'll start, and how to watch

In both rounds of polling, most Democratic primary voters identified the same five frontrunners as the candidates they expected to do the best: former Vice President Joe Biden, Sen. Bernie Sanders, Sen. Kamala Harris, Sen. Elizabeth Warren, and South Bend, Indiana Mayor Pete Buttigieg.

INSIDER's pre-debate July poll surveyed 1,184 American adults, 498 of whom identified themselves as likely Democratic primary voters and were asked to name the Democrats they thought would do best in the upcoming debates.

Compared to the first round of polling before the June debates, fewer Democratic primary voters included Biden and Sanders among the candidates they expected to perform well, and more counted Harris in that category.

• 52% of Democratic primary voters expect Biden to perform well in the July debates, a significant decrease from the 62% who thought he would do well in the June debates.
• 50% expect Harris to perform well in the July debates, a sizeable increase over the 37% of primary voters who expected her to do well in the June debates.
• 55% expected Sanders to do well in the July debates, compared to 58% who expected him to perform well in the June debates.
• The same percentage of Democratic primary voters expected Buttigieg to perform well in both the June and July debates and 57% expected Warren to do well in July, a slight uptick over the 55% who thought she would do well in June.

Biden came into the June debates in Miami as the clear frontrunner, leading every single pre-primary poll and weathering several small-scale controversies and gaffes.

But Harris took control over the debate and knocked Biden back on his heels with a powerful one-two punch over his record working with pro-segregation Democratic senators in the 1970s, and his ardent opposition to busing as a tool of racial integration.

Harris said to 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 it's personal and 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," she said.

"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," Harris added. "That little girl was me. So I will tell you that on this subject, it cannot be an intellectual debate among Democrats."

Read more: Kamala Harris was the breakout star of the 2nd night of Democratic debates, outperforming frontrunners Biden and Sanders

Biden struggled to adequately respond to Harris' fiery criticism of his record in the moment, later telling CNN's Chris Cuomo he "wasn't prepared" for the targeted attack on his record. Harris saw her poll numbers and fundraising surge while Biden's numbers slumped.

Sanders, who was also on stage with Biden, Harris, and Buttigieg, found himself on the defensive in the first half of the debate. Under pressure from the more moderate Sen. Michael Bennet, Sanders admitted that implementing Medicare for All would require raising taxes on the middle class and accused Rachel Maddow of mischaracterizing his record on gun control when she was directly quoting him.

Here's a breakdown of which candidates will be debating on which nights, and what percentage of Democratic primary voters listed them as a candidate they expected to do best in the upcoming July debates.

Debating on Tuesday, July 30:

• Sen. Bernie Sanders of Vermont (55% have high expectations for his July debate performance).
• Sen. Elizabeth Warren of Massachusetts (58%).
• Mayor Pete Buttigieg of South Bend, Indiana (28%).
• Sen. Amy Klobuchar of Minnesota (7%).
• Former Rep. Beto O'Rourke of Texas (16%).
• Author Marianne Williamson (2%)
• Gov. Steve Bullock of Montana (3.6%)
• Former Gov. John Hickenlooper of Colorado (3%)
• Former Rep. John Delaney of Maryland (3.6%)
• Rep. Tim Ryan of Ohio (5.2%)

Debating on Wednesday, July 31:

• Former Vice President Joe Biden of Delaware (52% have high expectations for his July debate performance).
• Sen. Kamala Harris of California (50%)
• Sen. Cory Booker of New Jersey (21%)
• Former HUD Secretary Julián Castro of Texas (12%)
• Andrew Yang (2%)
• Sen. Michael Bennet of Colorado (5.4%)
• Gov. Jay Inslee of Washington (2.6%)
• Sen. Kirsten Gillibrand of New York (10%)
• Rep. Tulsi Gabbard of Hawaii (3.2%)
• Mayor Bill de Blasio of New York City (4.6%).

Biden and Harris will face off again on the same night during the July debates, and will be joined by Booker and Castro, who distinguished themselves as strong debaters during the first round of debates in June.

Booker and Biden will also finally get to confront each other on the same debate stage taking shots at each other on the trail over Biden's record on race.

Read more: Presidential candidate Andrew Yang says he's ready to bounce back from a disappointing first debate performance

On the first night of the July debates, issues including healthcare and economic policy are likely to take center stage as the two progressive frontrunners Sanders and Warren will debate many of the more moderate candidates in the field, many of whom are vocal opponents to the single-payer Medicare for All healthcare plans backed by Warren and Sanders.

SurveyMonkey Audience polls from a national sample balanced by census data of age and gender. Respondents are incentivized to complete surveys through charitable contributions. Generally speaking, digital polling tends to skew toward people with access to the internet. SurveyMonkey Audience doesn't try to weight its sample based on race or income. Total 1,184 respondents collected July 20 to July 21, 2019, a margin of error plus or minus 3.01 percentage points with a 95% confidence level.