October’s Democratic presidential primary debate is a big one, literally. Twelve candidates will appear onstage together tonight, which The New York Times reports makes the debate the largest presidential primary debate in recorded American political history.

So who made the cut? The same 10 candidates from the September primary debate will appear, including front runners former Vice President Joe Biden, Massachusetts Sen. Elizabeth Warren, Vermont Sen. Bernie Sanders, South Bend, Ind., Mayor Pete Buttigieg, and California Sen. Kamala Harris. They’ll be joined by two candidates who hadn’t quite made the cut for the previous debate: Hawaii Rep. Tulsi Gabbard and billionaire executive Tom Steyer, who’ll make his Democratic National Committee-sanctioned presidential primary debate debut.

Candidates had to hit at least 2% in four DNC-approved polls and receive at least 130,000 unique donations by Oct. 1 to qualify for the debate. Gabbard has recently criticized the criteria needed to make the debate, arguing the DNC and the “corporate media are trying to hijack the entire election process.” She had threatened to boycott Tuesday’s debate in protest, but said Monday morning that she would be attending the debate.

The debate will be co-hosted by CNN and The New York Times and air live at 8 p.m. from Otterbein University in Westerville, Ohio.

The House of Representatives’s impeachment inquiry into President Donald Trump will likely loom large over the evening. The inquiry began after a whistleblower filed a complaint alleging the President pressured President Volodymyr Zelensky of Ukraine to investigate Hunter Biden and his father, Joe Biden, one of the leading Democratic presidential candidates. All eyes will be on how Biden and the other candidates navigate Trump pressuring Ukraine to investigate a political rival and his recent attacks on the former Vice President. Every Democratic presidential primary candidate has said they support the impeachment inquiry.

Sanders’s heart attack on Oct. 1 could also impact the debate; while he’ll take the stage in Ohio, Sanders’s aides have declined to say when he will be back on the campaign trail full time. His recent health issues could make other candidates hesitant to attack him directly, American University Professor of Government James Thurber tells TIME.

These factors definitely make for abnormal debate conditions, Thurber adds. “It’s not a regular cycle where you’re talking about the economy, the economy, the economy, and then a little bit about healthcare related to the economy,” he laughs.

However, Thurber says the economy will still likely come up for discussion, as will the usual Democratic issues of health care and immigration. The September debate featured a lengthy back-and-forth on Medicare for All, and similar arguments could well come up again. Following the Trump Administration’s recent announcement that it would pull U.S. troops from northeastern Syria — which critics argue effectively abandons Kurdish allies — foreign policy could receive greater air time. Climate change was also notably absent from the September debate, and moderators or candidates might attempt to address the omission by highlighting the topic.

Tuesday will also be a crucial chance for lower-polling candidates to gain attention before they face the higher requirements to appear in the November debate. Candidates will need at least 165,000 unique donors, with at least 600 each in at least 20 states. They also must hit 3% in at least four national or early state polls, or 5% in two early state polls. So far, only eight of the 12 candidates in the October debate have qualified.

Here’s everything you need to know about the October Democratic Debate. You can follow along with TIME’s live updates here.

When is the debate?

The October Democratic debate will take place on Tuesday, Oct. 15, and air live at 8 p.m. EDT from private liberal arts college Otterbein University in Westerville, Ohio, a suburb of Columbus.

This is the second DNC-sanctioned debate to be held on just one night. The DNC had said that if more than 10 candidates qualified for the September debate it would be split into two evenings, but only 10 made the cut. After Steyer and then Gabbard qualified for the October debate, some speculated that the debate would return to a two-night affair, but on Sept. 27 the DNC made it clear that the debate would remain one night. Citing a DNC official, CNN reported that the move was partially to expand viewership.

The debate will air on CNN, CNN International, CNN en Español, and stream on CNN.com’s homepage and NYTimes.com’s homepage. In addition, the debate will be available across mobile devices via CNN’s and New York Times‘ apps for iOS and Android, via CNNgo apps for Apple TV, Roku, Amazon Fire, Chromecast and Android TV, SiriusXM Channels 116, 454, 795, the Westwood One Radio Network and National Public Radio.

The candidates will stand onstage based on the average of the 10 most recent qualifying polls as of Oct. 2. This puts Biden, Warren, Sanders and Buttigieg closest to the middle.

Which candidates have qualified for the October Democratic Debate?

Democratic presidential candidate Sen. Amy Klobuchar speaks as Sen. Cory Booker looks on during the Democratic Presidential Debate at Texas Southern University's Health and PE Center on September 12, 2019 in Houston, Texas. Win McNamee—Getty Images

To qualify for the October debate, candidates had until 11:59 p.m. on Oct. 1 to amass 130,000 unique donors with 400 unique donors per state in at least 20 states. They also had to receive at least 2% support in four DNC-approved polls released between June 28 and Oct. 1.

All the candidates from September’s debate will appear onstage, along with new additions Gabbard and Steyer (who had both met the September debate’s donor requirements but not its polling thresholds). Gabbard qualified for and appeared in the first and second Democratic debates, and Steyer has never before appeared in a DNC-sanction debate; he entered the race in July.

Here’s every candidate in the October Democratic debate.

Former Vice President Joe Biden, 76

Biden served as President Barack Obama’s Vice President for two terms and represented Delaware in the U.S. Senate from 1973 to 2009.

New Jersey Sen. Cory Booker, 50

Booker was the mayor of Newark, N.J., from 2006 to 2013 and has since served as the first African American Senator from New Jersey.

South Bend, Ind., Mayor Pete Buttigieg, 37

Buttigieg has been the mayor of South Bend, Ind. since 2012 and was an intelligence officer in the U.S. Navy Reserve between 2009 and 2017. He would be the first openly gay presidential nominee for a major political party if he wins the primary.

Former HUD Sec. Julián Castro, 45

Castro served as the mayor of his hometown of San Antonio, Texas, between 2009 and 2014 and was the Secretary of Housing and Urban Development under President Obama between 2014 and 2017.

Hawaii Rep. Tulsi Gabbard, 38

An Iraq War veteran, Gabbard has represented Hawaii’s 2nd District since 2013, when she became the first American Samoan and the first Hindu member of Congress.

California Sen. Kamala Harris, 54

Harris has been a Senator for California since 2017 and came up through California politics, serving as the District Attorney of San Francisco from 2004 to 2011 and the first woman Attorney General of California from 2011 until 2017.

Minnesota Sen. Amy Klobuchar, 59

Klobuchar served as the County Attorney for Minnesota’s most populous county, Hennepin County, from 1999 to 2007 and become the first woman to be elected Senator from Minnesota in 2006.

Former Texas Rep. Beto O’Rourke, 47

O’Rourke ran unsuccessfully for Republican Ted Cruz’s Senate seat in 2018. He represented Texas’s 16th congressional district, which includes his hometown of El Paso, from 2013 to 2019.

Vermont Sen. Bernie Sanders, 78

A self-described democratic socialist, Sanders ran for the 2016 Democratic nomination and lost to former Secretary of State Hillary Clinton. Sanders has served as a Senator for Vermont since 2007 and previously was Vermont’s sole congressional representative from 1991 to 2007.

Billionaire executive Tom Steyer, 62

Steyer started the hedge fund Farallon Capital and founded the political groups NextGen America and Need to Impeach, pouring millions of his own money into television ads and digital campaigns calling for President Trump’s impeachment.

Massachusetts Sen. Elizabeth Warren, 70

Warren became the first woman Senator from Massachusetts in 2013 and previously taught law, specializing in bankruptcy. She proposed the original idea for the Consumer Financial Protection Bureau in 2007 while still teaching at Harvard Law School.

Entrepreneur Andrew Yang, 44

Yang founded Venture for America, a nonprofit and fellowship focused on creating jobs in cities across America. He’s known for advocating about the threat of automation.

Who didn’t qualify?

By the Oct. 1 deadline, self-help author Marianne Williamson had met the donor requirements but not the polling threshold.

Six candidates met none of the requirements: Colorado Sen. Michael Bennet; Montana Gov. Steve Bullock; Former Maryland Rep. John Delaney; Miramar, Fla., Mayor Wayne Messam; Ohio Rep. Tim Ryan and Former Pennsylvania Rep. Joe Sestak.

Eight candidates have dropped out of the race: New York Sen. Kirsten Gillibrand, Former Alaska Sen. Mike Gravel, former West Virginia state senator Richard Ojeda, Former Colorado Gov. John Hickenlooper, Washington Gov. Jay Inslee, Massachusetts Rep. Seth Moulton, California Rep. Eric Swalwell, and New York City Mayor Bill de Blasio, who dropped out of the race after the September debate.

Who’s moderating?

CNN and the New York Times will co-host the debate. CNN anchors Anderson Cooper and Erin Burnett and New York Times National Editor Marc Lacey will moderate.

This is the second DNC-sanctioned debate CNN has hosted this election cycle; the network also hosted the second presidential primary debate in July in Detroit.

Only Cooper has moderated a presidential debate in the past. It’s been over a decade since The New York Times has hosted a debate.

Debate moderator Anderson Cooper looks during the CNN Democratic Presidential Primary Debate between Democratic presidential candidate Hillary Clinton and candidate Senator Bernie Sanders at the Whiting Auditorium at the Cultural Center Campus on March 6, 2016 in Flint, Michigan. Scott Olson—Getty Images

What are the big issues that will likely come up?

Political analysts tell TIME that the issue of impeachment will likely come up during the evening. At least 225 members of the House of Representatives have said they support the impeachment inquiry (all Democrats except one), and all 19 Democratic presidential primary candidates have said they support the inquiry. Trump is only the fourth President in U.S. history to face impeachment, and the moderators will likely feel the need to acknowledge the historic circumstances. Viewers might also be interested; Hans Noel, an associate professor at Georgetown University’s Department of Government, tells TIME that anyone who’s engaged enough in politics to watch the debates likely has paid attention to what’s going on in Washington.

“We’ll almost certainly [hear] more about President Trump in this debate than we did in the previous debates,” Jennifer Victor, an associate professor of political science at George Mason University’s Schar School Policy and Government, writes in an email.

While every candidate supports the impeachment inquiry, they vary on the degree to which they’ve openly called for the President’s impeachment itself, let alone removing Trump from office. Gabbard was one of the lone Democratic holdouts in Congress to oppose the inquiry until she switched her position on Sept. 27. Warren has called for Trump’s impeachment since April, but Biden called for Trump’s impeachment for the first time on Wednesday.

The issue could particularly help Steyer, who’s called for Trump’s impeachment for years and has poured millions of his own money into a campaign to accomplish just that. “He might even be the one to bring it up,” says Noel. But Noel points out that other candidates have also taken strong stances on impeachment, including more moderate candidates like Amy Klobuchar, and he suspects viewers will hear “a chorus of agreement” on the issue.

Kyle Kondik, the managing editor of political forecaster Sabato’s Crystal Ball at the University of Virginia Center for Politics, writes in an email that “one wild card” is whether any of the Democrats attempt to attack Biden along the same broad lines as President Trump has done in recent weeks. Not Trump’s specific attacks about connections to Ukraine, but arguing “more broadly about members of Biden’s family seeming to profit on the former vice president and senator’s name.” There has been no evidence of wrongdoing by Biden or his son.

“This is a dangerous path because it could be taken by Trump as validation,” Kondik writes. “[B]ut Biden is also still the leading candidate in the field, and all the other candidates have an interest in him falling off.”

Martha Kropf, a professor of political and public administration at University of North Carolina, Charlotte, tells TIME to also watch for how candidates specifically handle the topic of Hunter Biden, who served on the board of Ukrainian natural gas company Burisma while his father was involved in the Obama administration’s Ukraine policy. Some candidates have already addressed the issue. O’Rourke told reporters last week, “I would not allow a family member, anyone in my cabinet to have a family member, to work in a position like that.” On Sept. 29, Booker told CNN’s Jake Tapper, “I just do not think that children of presidents, of vice presidents during an administration should be out there doing that,” although he added that he would “be standing firmly in defense of Joe Biden.”

Political analyst Stuart Rothenberg, senior editor of Inside Elections with Nathan Gonzales, writes in an email that taxes and spending “seem to come up in every debate” and he’d predict “at least a foreign policy question or two,” especially given the Trump Administration’s recent announcement to withdraw troops from northern Syria. Kropf also TIME in an email that she suspects foreign policy to be “huge.”

On top of foreign policy, Thurber of American University predicts the economy — specifically the suppression of wages and quality of life for workers — will also likely come up again.

Which candidates might clash onstage?

Democratic presidential hopefuls California Senator Kamala Harris and Former Texas Representative Beto O'Rourke share a laugh during a break in the third Democratic primary debate of the 2020 presidential campaign season hosted by ABC News in partnership with Univision at Texas Southern University in Houston, Texas on September 12, 2019. ROBYN BECK—AFP/Getty Images

“We’ve got an interesting situation where Biden’s being attacked by the President and Bernie has had a serious heart attack,” Thurber says. That might affect the dynamics of how other candidates criticize the former Vice President and Senator.

Because Warren has steadily climbed in national and state-wide polls, Noel says there’s potential for a direct clash between Warren and Biden — and that Sanders might want to reclaim his position as a possible alternative to Biden by going after Warren.

Rothenberg suggests watching Biden “since his previous debate performances have been less than ideal,” adding that “Buttigieg, Harris, Klobuchar and possibly Booker could benefit if Biden stumbles badly.”

Rothenberg also predicts that “[s]omeone (and possibly more than one) may go after Warren, now that she is at or near the top of the pack.”

Thurber predicts that Buttigieg, who’s polling in the top five with an ideological bent similar to Biden’s, might have conflict with Warren or Sanders in an attempt to garner more support.

Harris, who had an initial spike after she sparred with Biden in the first debate, has since decreased to fifth in Real Clear Politics’ national polling average. She’ll likely attempt to inject another burst of life into her campaign using the October debate. “This is maybe her last chance to really claw her way into that top group. She’s right on the edge of it; she’s been slipping out,” Noel says. “[She] probably has the biggest incentive to do something bold.”

Noel says that Booker and O’Rourke also need to do something to draw attention to their candidacy. “Anything that [they] can do to get air time is the goal,” he explains. Candidates who have consistently been on the edge of qualifying need to do something to break out, he adds, “or they’re going to have a hard time raising money and most of the attention is going to turn to the front runners.”

He said that while it’s still very early in the campaign, “in terms of the invisible primary, in terms of the donors and organizing of campaigns and resources … it’s really quite late.” He also said some of the lower-polling candidates may start thinking of dropping out.

The two new additions since September, Gabbard and Steyer, could also affect the dynamic onstage. Gabbard criticized Harris for her record as a prosecutor in the second debate, and may go on the attack once more in an attempt to draw attention to herself. She also could highlight her experience as an Iraq War veteran during questions on foreign policy. While Steyer has qualified for the November debate, he’s relatively new to Democratic viewers, and will be looking to make a name for himself.

Don’t expect this debate to be too different from the last one, however. When asked about the addition of the two new candidates, Noel says, “My guess is, while it might be entertaining, it probably won’t affect things too much.”

Where do the candidates stand in the polls?

The race hasn’t changed fundamentally since the September debate, Rothenberg writes. “Nobody outside the top three has taken off.”

Noel tells TIME that the only real trend he’s seen has been the continued rise of Warren from a more “second-tier” candidate to neck-in-neck with Biden. Since the summer she’s risen in polls both nationally and in early primary states. Noel adds that Warren’s rise has been “at the expense of Sanders and a little bit of expense of Harris.”

Thurber also explains that “it’s way too early” for polls to be particularly meaningful. At this stage of the election, much of what they’re measuring is name recognition.

Caveats aside, according to RealClearPolitics’s national polling average on Oct. 10, the candidates in the debate have the following polling averages:

27.0% Biden

26.8% Warren

14.8% Sanders

5.2% Buttigieg

4.4% Harris

2.8% Yang

1.6% O’Rourke

1.2% Booker

1.2% Klobuchar

1.0% Castro

0.6% Gabbard

0.6% Steyer

Write to Madeleine Carlisle at madeleine.carlisle@time.com.