On Wednesday, U.S. Sen. Elizabeth Warren of Massachusetts and former U.S. Rep. Beto O’Rourke of El Paso will take center stage among 10 Democratic presidential candidates on the first of two successive nights of televised debates from Miami. It might prove a moment of truth for both candidates.

For Warren, who for months has been gaining steadily at the expense of U.S. Sen. Bernie Sanders of Vermont, it is an opportunity to step forward and supplant Sanders as former Vice President Joe Biden’s leading rival. The next night, Biden, the far-and-away early-front runner in the polls, will stand side-by-side with Sanders, their stage placement based on their superior polling numbers, headlining the second debate with its own lineup of 10 candidates.

For O’Rourke, whose once promising campaign appears to have peaked the day he announced, it is a stroke of fortune that by luck of the draw he found himself assigned to the Wednesday debate stage where, despite running a distant sixth in national polls, he still runs ahead of the other eight members of that night’s cast, which includes a governor, two U.S. senators, two U.S. representatives, a former member of Congress, the mayor of New York City and his fellow Texan, Julián Castro, the former mayor of San Antonio and secretary of housing and urban development in the second Obama administration.

The debate will provide O'Rourke a renewed opportunity to demonstrate to voters, pundits and donors that he deserves to be in the top tier of candidates, and that he is not the self-absorbed lightweight depicted in story after story in national media outlets.

“You know and I know that the narrative is mostly garbage,” O'Rourke's digital director, Rob Flaherty, wrote to the Team Beto email list June 10.

The debate might provide O'Rourke the opportunity to restake his claim to be the next-generation candidate for 2020, something that seemed within his grasp after his out-of-nowhere run for the U.S. Senate last year gained a national following, raising more money than any Senate candidate in history and propelling him to within 2.6 points of defeating U.S. Sen. Ted Cruz, R-Texas.

But days before O'Rourke entered the presidential race amid a frenzy of press attention befitting a front-runner, Pete Buttigieg, the 37-year-old mayor of a Midwestern city of scarcely more than 100,000 people, broke through with an appearance on a CNN town hall conducted in Austin during South by Southwest. In short order, Buttigieg had stolen O'Rourke's thunder, appearing at once fresher, more seasoned and, as a gay man with a husband, more culturally cutting-edge, than O'Rourke.

'The shadow of racism'

On Thursday, Buttigieg will be standing to the immediate right of Biden, who is 76. To Biden's left will be Sanders, who is 77, offering what will be an all-too-obvious tableau.

Both Biden, the overwhelming favorite of black voters, and Buttigieg, whose great weakness so far as has been his inability to make any headway with that core Democratic Party constituency, might be preoccupied with questions of race Thursday.

Buttigieg was back in his hometown of South Bend, Ind., much of the past week after a white police officer shot and killed a black man who the officer said had flashed a knife at him. The officer's body camera had been turned off.

"All police work and all of American life takes place in the shadow of racism, which hurts everyone and everything it touches," Buttigieg wrote in an email to supporters Thursday. "Historic racism, present-day racism, and generational racism — they all secrete a kind of poison into the bloodstream of this country. And we must join together to make things right, no matter how demanding that process may be."

The shooting rubbed raw already tender relations between Buttigieg and some in his city's African American community, posing a challenge for a candidate who, like O'Rourke before him, had burst upon the national scene in a manner that might have excited impossibly high expectations.

"I'm certainly intrigued by Buttigieg, because he's one of those who when you hear him interviewed and you hear him talk, you just stop what you're doing because he’s such a captivating speaker and so smart," said Adam Schiffer, a Texas Christian University political scientist who studies presidential nominating contests. "But no matter how smart, how visionary, anyone who thinks they can leap from South Bend mayor to president, there’s some screw loose there, there’s something that makes me not trust their judgment."

Biden, meanwhile, stirred controversy Tuesday at a New York City fundraiser. Talking about the importance of consensus-building, Biden spoke with some nostalgia of the civility he had maintained with segregationist U.S. Sens. Herman Talmadge of Georgia and James Eastland of Mississippi early in his Senate career, despite their political ideological differences.

Biden's remarks drew criticism from the two black U.S. senators in the Democratic race — New Jersey's Cory Booker, who will appear on Wednesday night, and California's Kamala Harris, who is running just ahead of O'Rourke in the polls and will be just to the left of Sanders on Thursday's debate stage.

Criticism of Biden also came from Ta-Nehisi Coates, the writer who was the star witness at Wednesday's congressional hearing on reparations for slavery, an issue that has gained currency among many of the Democratic candidates this year thanks in large part to Coates' 2014 "Atlantic" article “The Case for Reparations."

"I mean, Joe Biden shouldn’t be president," Coates said Thursday on the radio show, "Democracy Now!" "You know, obviously, I don’t think I’m breaking any news here. You know, if he ends up being the nominee, better him than Trump, but I think that’s a really, really low standard."

'The invisible primary'

This week's debates are the first big omnibus event of the 2020 presidential campaign. The Democratic National Committee set a limit of 20 candidates and set polling and/or fundraising requirements to qualify.

There will be another set of debates in late July, and then, with the bar raised, again in September.

It is way too early for most Americans to care. The first voting, in Iowa, is not until Feb. 3.

"The bottom line here is that a whole lot of people are not going to watch," said Mary Stuckey, a Penn State University communications professor, who studies political and presidential rhetoric.

But activists, donors and the media — who will create the frame through which most Americans will form their takeaway of what happened, of who won and who lost — will.

"This is the invisible primary. This is the winnowing period," Stuckey said. "So some of these really sort of unknown candidates don't make a big splash, and they don't get the money, they're gone. They have to be done. It's not sustainable."

Ten candidates debating in two hours means that each candidate can hope for 10 or 11 minutes, creating a potentially desperate urgency among those with the most tenuous standing.

‘What is likely to happen is that somebody in the lower tier may say, `I have one shot to land a haymaker, maybe I can do it this one time,’” said Jeffrey Engel, founding director of Southern Methodist University’s Center for Presidential History. "As we all know, the odds of that in boxing as in anything else is very low."

Castro's chance

Castro has a compelling story to tell. His grandmother crossed the border from Mexico at age 7, with her little sister in tow. Now his twin brother, Joaquin, is in Congress and he is running for president.

"He’s really chill, he’s really laid back, he's pleasant to listen to, he's got good ideas, but you've got to have something to stand out," Schiffer said of Julián Castro.

And so far, Castro hasn't. He is polling at less than 1% in the Real Clear Politics polling average, and at only 3% in his home state in the University of Texas/Texas Tribune poll released Monday.

"He was one of the earliest to announce, and I think that might have hurt him," said Joshua Scacco, an expert on political communication at the University of South Florida.

"In some ways, this is his grand reopening," Scacco said of Castro's opportunity Wednesday. "He's the restaurant that’s been open for a while that nobody’s been going to, so he has to rebrand and remarket."

And Castro has the potential to surprise.

Among the most arresting responses when The New York Times asked 21 of the candidates 18 questions and recorded their responses on video was Castro's answer to the very first question: "In an ideal world, would anyone own handguns?"

"In an ideal world, people would not own handguns, and there are a number of countries around the world where people do not own handguns, where they’re not permitted, and we see that those countries have more safety, greater safety, less violent deaths and so forth," Castro said. "However, we also recognize in the United States that the Supreme Court in the Heller decision has ruled that people do have the right to bear arms."

That was just the beginning of a long and thoughtful response.

Warren's 'big story'

SMU political scientist Matthew Wilson said the incentive to stand out might pull the Democratic field further left than will prove helpful in the general election.

"The people who are in the low single-digits, they don’t have the luxury of worrying about the general election at this point," Wilson said. "They have to stand out from this huge pack of Democratic rivals, and so they’ll tack as far leftward and in as dramatic a way as they can to try to get some buzz among the Democratic primary electorate."

"Joe Biden has to really carefully calibrate how far he’s willing to tack left to fend off Democratic primary rivals, but he can do that because he’s the front-runner," Wilson said.

Meanwhile, Sanders, a self-described democratic socialist, does not have to tack left. He's been there his entire career, and he's not budging.

On Thursday, Nate Silver of the statistical analysis site FiveThirtyEight, identified two meaningful shifts in polling: "One is that Elizabeth Warren has gained at Bernie Sanders’s expense," Silver wrote. "The other trend is that Beto O’Rourke and Pete Buttigieg have swapped places. At the end of March, O’Rourke was at 9.3 percent and Buttigieg was at 2.6 percent; now, it’s Buttigieg at 7.7 percent and O’Rourke at 3.6 percent."

Perhaps presaging Warren's current moment were major profiles in the last week in the New Yorker and The New York Times Magazine.

"She’s got a big story about where the country is and where it’s going," said John Murphy, who studies the history of political rhetoric at the University of Illinois.

Murphy said the concern among some Democrats that Warren, who turned 70 Saturday, might appear to be a reprise of Hillary Clinton, 71, is unfair.

"Clinton’s problem was that she had all these issues, but there was no larger narrative she was hanging it on,” Murphy said. “That marks the difference between the two. Warren has a good story.'

Of Clinton, he said, “She’d been in public life since 1975; you’re not suddenly going to alter perceptions."

“I think Warren has figured out her public persona. In the past, her speech at the Democratic National Convention in 2016 was not very good," Murphy said. "But what she’s playing to now is her skill as a college teacher. Remember, she was a good teacher (at the University of Texas and Harvard law schools). Students liked her. And so more and more, the speeches are the way she would be dynamic and charismatic in front of a group of students."

Warren's problem could be beating expectations.

"She's expected to do well, so if she does well, she doesn't win a lot because the bar is set high for her. If she does badly, she loses big," Stuckey said.

O'Rourke, on the other hand, might finally benefit from diminished expectations.

"I will say this for Beto, his campaign has had such a terrible string of bad stories, his campaign has nowhere to go but up," said Scacco.

"The problem Beto faces is the continuing question of why he is not running for Senate with (U.S. Sen. John) Cornyn (R-Texas) up for reelection," Scacco said.

For that Senate seat, MJ Hegar, a decorated Air Force helicopter pilot, who ran a close race against U.S. Rep. John Carter, R-Round Rock, for Congress in 2018, is seeking the Democratic nomination. And O'Rourke has said that she, or another candidate, will beat Cornyn, and that, his own standing in the national polls notwithstanding, the enthusiastic crowds he is encountering day after day on the campaign trail, tell a different story of his standing in the presidential race.