The Democratic National Committee announced on Friday that the sixth Democratic primary debate would be held in December at the University of California, Los Angeles, while ratcheting up the polling and donor criteria for candidates to qualify for a coveted spot onstage.

The debate will be held on Dec. 19 and sponsored by PBS NewsHour and Politico. The format and moderators have not yet been announced. Another debate is scheduled for Nov. 20, sponsored by MSNBC and The Washington Post.

In an effort to narrow the number of candidates after the largest debate ever in October, the D.N.C. is raising its thresholds for the December debate. It will require candidates to have at least 200,000 individual donors and meet one of two polling requirements: They must either receive 4 percent support in four national or early-state polls conducted by qualifying pollsters, or 6 percent support in two polls in the four early states — Iowa, New Hampshire, Nevada and South Carolina.