Widely viewed as a talented debater, Warren is well positioned to showcase her strengths, strategists say.
"I don't think anyone else on that night has her level of skill and her level of experience in this format," said Maria Cardona, a Democratic strategist. "I think she should look at this as an opportunity to really shine and come out of the first night as the one that is dominating the conversation."
Yet Warren could still face challenges. The other candidates on stage aren't as well known and could use the moment to take aggressive stances against Warren in an effort to find a breakout moment.
"She's liable to have a target on her back and a lot of people potentially coming after her on that stage," said Charles Chamberlain, the chairman of the progressive political action committee Democracy for America. "But on the other hand, that will let people see how she handles attacks and can fend them off."
Beyond Warren, the candidates who will debate tomorrow are senators Cory Booker of New Jersey and Amy Klobuchar of Minnesota; Represntatives Tulsi Gabbard of Hawaii and Tim Ryan of Ohio; former Representatives Beto O'Rourke of Texas and John Delaney of Maryland; Washington Governor Jay Inslee; New York City Mayor Bill de Blasio and ex-Obama Housing Secretary Julián Castro.
One split that could emerge centres on "Medicare for All," the single-payer health plan introduced by Vermont Senator Bernie Sanders, a fellow Democratic presidential candidate, and supported by Warren and others. But some candidates are not fully on board, preferring more incremental reforms. Delaney has been especially vocal in his criticism.
With so many White House hopefuls on stage, it could be difficult to dive too deep on any given issue.
NBC News, which is hosting the debate, said candidates will have 60 seconds to answer questions and 30 seconds for follow-ups. They will be allowed closing statements but no openers.
All the candidates are competing ahead of a major fundraising deadline that will have lasting implications. The end of the second fundraising quarter on Monday NZT gives candidates a chance to make a splash with strong numbers ahead of the mid-July deadline to report that information to the Federal Election Commission.
A strong debate performance could fuel more donations, which is critical to the candidates' ability to participate in future debates. The Democratic National Committee is enforcing more stringent requirements for participating in the presidential primary debates in September, so candidates who are struggling to gain a foothold may not have another similar opportunity on a nationally televised stage unless they are able to significantly boost their standing in the polls and fundraising numbers.
"For some of them, this might be their best opportunity to land a blow," said Joel Payne, a Democratic strategist.
The debate will unfold as many Democratic voters are just beginning to tune in.
Only 35 per cent of registered Democrats say they're paying close attention to the campaign, according to a new poll from AP-NORC Centre for Public Affairs Research. Two-thirds say they're paying some or no attention.
"People may have heard (the candidates') names, but they couldn't pick them out and don't know much about them," said Jesse Ferguson, a veteran Democratic strategist.
"None of them are going to seal the deal in the first debate, but they need to get people interested enough to want to learn more."
The debate's second day features more of the leading Democrats in the race. Former Vice-President Joe Biden will stand at centre stage with Sanders at his left and Mayor Pete Buttigieg of South Bend, Indiana, at his right.
Biden has come under fire from fellow Democrats after recently recalling that the Senate was once a more civil place, pointing to his work with two segregationist former senators.
The remarks elicited condemnation from his rivals, notably Booker and Senator Kamala Harris of California, who raised questions about Biden's understanding of the history of segregation. Booker, who was among Biden's sharpest critics, called on him to apologise.
Were the two candidates to share a stage, the episode could have been a defining moment of the debate, with the two men discussing the issue in real time. But Booker will take the stage tomorrow, with Biden and Harris among the candidates to follow on Friday.
If Booker were to bring up the episode, or respond to a moderator's question about it, Payne said, "it's almost like he's attacking him in absentia."
Several of the candidates went to Florida early to raise money or court voters in the critical battleground state.
Buttigieg held two Florida fundraisers yesterday and stayed in Florida for debate preparation.
Warren was in the state today to campaign for her new proposal to boost election security.
- AP
ABOUT THE DEMOCRATIC DEBATES
The debates will take place over two days — tomorrow and Friday — in Miami, Florida.
Time: NBC will broadcast the debates from from 1pm to 3pm NZT.
Candidates: Each debate will have 10 candidates.
Tomorrow:
Former Housing Secretary Julián Castro
Former Representative Beto O'Rourke of Texas
Former Representative John Delaney of Maryland
Mayor Bill de Blasio of New YorkRepresentative Tim Ryan of Ohio
Representative Tulsi Gabbard of Hawaii
Senator Amy Klobuchar of Minnesota
Senator Cory Booker of New Jersey
Senator Elizabeth Warren of Massachusetts
Washington Governor Jay Inslee
Friday:
Author Marianne Williamson
Entrepreneur Andrew Yang
Former Vice-President Joe Biden
Colorado Governor John HickenlooperMayor Pete Buttigieg of South Bend, Indiana
Representative Eric Swalwell of California
Senator Bernie Sanders of Vermont
Senator Kamala Harris of California
Senator Kirsten Gillibrand of New York
Senator Michael Bennet of Colorado
Standings: Yesterday's Morning Consult poll
Biden 38%, Sanders 19%, Warren 13%, Buttigieg 7%, Harris 6%, O'Rourke 4%, Booker 3%
Rules: Candidates will have a minute to answer a question, 30 seconds for follow-up answers. There will be five segments, and closing statements.
Moderators: NBC News' Lester Holt, Savannah Guthrie and Chuck Todd, MSNBC's Rachel Maddow and Telemundo's José Diaz-Balart.
Online stream: NBCNews.com, NBC News apps, Telemundo, NBC News' Facebook, Twitter and YouTube.
