Everything you need to know about tonight’s Democratic presidential debate

The seventh Democratic presidential debate is scheduled for Tuesday night, and will be the smallest and least diverse to date.

The field of candidates has narrowed and the campaigns of the main candidates for the White House have begun to adopt a harder tone among themselves, even generating clashes between old friends like Bernie Sanders and Elizabeth Warren.

This Tuesday's debate is the last one before the Iowa caucus, on February 3. You can follow the coverage minute by minute here.

The two candidates who have fought the most in recent weeks - former Vice President Joe Biden and Sanders, the independent Vermont senator - will be side by side in the center of the stage.

This is what you need to know about the debate:

When and where?

The two-hour debate, organized by CNN and the Iowa newspaper, The Des Moines Register, will begin at 9:00 pm (Eastern time) and will take place at Drake University, in Des Moines.

The event has three moderators: Wolf Blitzer and Abby Phillip of CNN, and Brianne Pfannenstiel of the Register.

Which candidates will be on stage?

Qualification requirements to participate in discussions have seen a rapid increase in requirements. To qualify for tonight, candidates were required to raise money from 225,000 unique donors and reach at least 5% in four different national polls, or 7% in two polls of the states that vote first.

The six candidates who qualified are Biden, Sanders, the senator for Massachusetts Warren, the senator and former mayor of South Bend, Indiana Pete Buttigieg, the senator for Minnesota Amy Klobuchar, and billionaire philanthropist Tom Steyer.

New Jersey Senator Cory Booker - who left the race on Monday - and businessman Andrew Yang, both candidates of color, managed to accumulate donations but not the results in the polls . Yang had been the only candidate of color in the December debate.

To determine where the participants will be located on the stage, surveys were conducted. The candidates with the best results will be placed in the center, while those with less support are deployed to the sides. From left to right, the order will be: Steyer, Warren, Biden, Sanders, Buttigieg and Klobuchar.

What are the rules or format?

There will be no opening speeches, but candidates may make closing statements. Each candidate will have 75 seconds to answer questions, 45 seconds for rebuttals and 15 for clarifications, event organizers said Tuesday.

Where to watch the debate?

The debate will be broadcast live on CNN and CNN International, as well as CNN.com and DesMoinesRegister.com.

NBCNews.com will cover the debate with a liveblog that will include data verification and analysis. Telemundo will also offer minute by minute coverage.

When is the next round?

The calendar of debates that so far set only one per month will change in February when three debates will be scheduled in the states that vote first.

The first, which will be presented by ABC, WMUR and Apple News, is scheduled for February 7 at St. Anselm College in Manchester, New Hampshire.

The second, organized by NBC and MSNBC, will take place in Las Vegas on February 19.

The third will take place on February 25 in Charleston, South Carolina, and will be presented by CBS News, the Congressional Black Caucus Institute and Twitter.

If the process of political trial against President Donald Trump is still going on at that time, it could cause serious programming problems for three of the six candidates participating, as the acting senators will have to act as jurors at the trial.

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