Two other debates have been previously scheduled for February: One on Feb. 19 in Las Vegas and another on Feb. 25 in South Carolina.

After South Carolina’s Feb. 29 primary, 14 states will vote on March 3, the delegate-rich Super Tuesday that includes California, North Carolina, Virginia and Texas. Another six states — including Michigan, Missouri and Washington state — will vote on March 10.

So far, five candidates have qualified for the Nevada debate, according to POLITICO's tracking of public polling and national delegate counts: Joe Biden, Pete Buttigieg, Amy Klobuchar, Bernie Sanders and Elizabeth Warren.

Mike Bloomberg is also on the precipice of qualifying for the Nevada debate. The former New York City mayor needs to hit at least 10 percent in one more poll approved by the DNC by Tuesday to qualify for the debate, which would be the first time the billionaire has hit the requirements to participate in a party-sanctioned debate.

Candidates can qualify for the Nevada debate by hitting at least 10 percent in four DNC-approved polls (or 12 percent in two polls in Nevada and South Carolina), or by winning one delegate to the national convention out of Iowa and New Hampshire. It is the first debate without a donor threshold, which opened the door to Bloomberg’s possible qualification. The DNC has not announced how candidates can qualify for the South Carolina debate, which is in eleven days.

However, the Democratic field will likely be drastically smaller come the Arizona debate. Several candidates are relying on bounce-back performances in either Nevada or South Carolina, and the overwhelming number of delegates being awarded on Super Tuesday could knock others out of the race.

DNC chairman Tom Perez noted the significance of holding the debate in Arizona, an emerging presidential swing state. “This debate will showcase our Democratic presidential candidates, highlight Trump's record of broken promises and make it clear that Democrats are fighting to give Arizonans a better future,” he said in a statement accompanying the announcement.