(CNN) The Democratic National Committee on Monday announced higher polling and donor thresholds to qualify for the party's 2020 presidential primary debates -- changes that could soon reduce the number of candidates on stage and, in turn, effectively winnow the field.

For the fifth presidential debate, set for November, candidates will have to reach 3% in at least four DNC-approved polls of Democratic voters nationally or in one of the four early-voting states -- Iowa, New Hampshire, Nevada and South Carolina. That's a 1 percentage point increase over the threshold for the September and October debates.

The DNC is also giving candidates a new option: Instead, they can reach at least 5% in two polls of the early-voting states.

The polls must come in a window between September 13 and a week before the November debate. The DNC has not yet announced the date of that debate.

Candidates will also have to raise money from 165,000 separate donors -- including a minimum of 600 donors each in at least 20 states or territories. That's up from the current minimum of 130,000 donors.

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