WASHINGTON — The Democratic National Committee on Thursday unveiled the early outlines of its 2020 presidential primary debate plans, a process that could allow a large number of candidates to face off over two consecutive evenings in at least a dozen planned debates.

Tom Perez, the chairman of the committee, announced that the party would hold six debates in 2019 and the rest in the first six months of 2020. In a shift from tradition, none are scheduled for the early-primary states of Iowa, New Hampshire, South Carolina and Nevada until 2020.

With nearly three dozen Democrats pondering a presidential bid, party officials anticipate a rush of candidates eager to grab a spot in the nationally televised forums. Depending on the size of the field, the committee may decide to split the debate over two consecutive evenings in the same location, Mr. Perez said, and would conduct a random selection process that would take place publicly to determine which candidates speak on which nights. He did not elaborate on how that process might work.

[Make sense of the people, issues and ideas shaping American politics with our newsletter.]

Mr. Perez said the committee had not set a maximum number of candidates who could appear on the stage and was planning for the possibility of a “double-digit field.”