The Democratic National Committee unveiled the new qualifying threshold for the upcoming March debate in Arizona, scrapping the existing pathways, and upping the delegate requirement significantly in what is now essentially a two-person race For the matchup, which will be hosted by CNN and Univision on March 15, ahead of a slate of primaries in some key battlegrounds -- including Arizona, Florida, Illinois and Ohio -- the three presidential candidates still in the Democratic contest must only meet one threshold: earning at least 20% of the delegates awarded so far in the campaign through the deadline.From the start of the primary season through the next debate day, also the deadline, a total of 1,870 delegates will be allocated across the field. In the delegate hunt, candidates will need to score at least 374 delegates, according to an ABC News analysis.The two presidential hopefuls leading the delegate scoreboard are former Vice President Joe Biden and Vermont Sen. Bernie Sanders , who have already hit the threshold, with 566 and 495 pledged delegates, respectively, from the first four early nominating contests through Super Tuesday, which still has some votes outstanding.The other contender still in the race is Hawaii Rep. Tulsi Gabbard, whose two delegates from the U.S. territory American Samoa, where she was born, are currently far short of the needed threshold.Candidates have until 9 a.m. ET on March 15 to secure the necessary pledged delegates, as calculated and reported by the Associated Press and CNN, and can collect delegates from across contests in: Alabama, American Samoa, Arkansas, California, Colorado, Democrats Abroad, Idaho, Iowa, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Nevada, New Hampshire, North Carolina, North Dakota, Northern Mariana Islands, Oklahoma, South Carolina, Tennessee, Texas, Utah, Virginia, Vermont and Washington.In a primary season that had up to twelve candidates on a single stage, the new threshold marks a sharp departure from the previous and more inclusive rules.The new qualifying rules makes it almost certain the next showdown will be between the two front-runners. At this point in the race, with still a number of nominating contests before the deadline, Biden has roughly 30% of the 1,870 delegates that will be awarded by March 15, and Sanders has about 27%, according to an ABC News analysis. Gabbard currently has less than one percent of the delegates that have already been and will be awarded by the deadline.For those delegates allotted to candidates who have since suspended or "otherwise discontinued" their campaigns, according to the DNC, will be allocated as "uncommitted."The national party, in announcing the new qualifying rules, added, "in the event that the Associated Press or CNN have not allocated a portion of the delegates available in any of the above contests due to the ongoing tabulation of votes, such unallocated delegates will not be counted in the Total Delegate Allocation."The new rules come after a series of candidates exited the race, including Massachusetts Sen. Elizabeth Warren, former New York City Mayor Michael Bloomberg, Minnesota Sen. Amy Klobuchar and former South Bend, Indiana Mayor Pete Buttigieg, since the South Carolina primary on Feb. 29. After Biden's resounding victory, Bloomberg, Klobuchar and Buttigieg all backed his bid for the White House.On Friday, former Massachusetts Gov. Deval Patrick -- who dropped out of the presidential race on Feb. 12 -- announced he, too, was endorsing the former vice president.Warren, a more left-leaning Democrat who sought to build her own lane between the progressive and moderate factions, would not signal who she plans to endorse or when, telling MSNBC, "I had lot I needed to do today. I'll get up tomorrow morning and start thinking about that question."Two other candidates that ended their campaigns last month, businessman Tom Steyer and entrepreneur Andrew Yang, have not yet endorsed a candidate either.The DNC is expected to host a total of twelve debates throughout the primary.