LOS ANGELES — The sixth Democratic presidential primary debate will be hosted by PBS and Politico in Los Angeles on December 19, the Democratic National Committee announced Friday.

The DNC has also stepped up the polling and fundraising thresholds for candidates to qualify for the debate, which will make it even more difficult for the lagging candidates to catch up and could winnow the field further.

To make the stage at the University of California Los Angeles, candidates will need to hit 4 percent in at least four DNC-approved national or early voting state polls — up from 3 percent for the November debate — or, alternatively, receive 6 percent or more support — up from 5 percent — in at least two approved early-state polls in Iowa, New Hampshire, South Carolina or Nevada.

Additionally, candidates also have to receive at least 200,000 unique donations, — up from 165,000 for the November debate — and a minimum of 800 unique donors per state in at least 20 states.

Democratic National Committee Chair Tom Perez said in December 2018 that the party wanted to host 12 debates — six in 2019 and six in 2020, with the last happening in April.

Viewership for the debates has remained elevated compared to previous election cycles.

The field for the Democratic presidential nomination remains deep, with nine candidates appearing to have qualified for the upcoming fifth debate, according to an unofficial NBC News tally. That debate is scheduled for Nov. 20 and will be hosted by MSNBC and The Washington Post.

The deadline to qualify is December 12 at 11:59 p.m., the DNC said.

Former Vice President Joe Biden and Sen. Elizabeth Warren, D-Mass., both lead in some key polls. After them, Sen. Bernie Sanders, I-Vt, and South Bend, Indiana, Mayor Pete Buttigieg round out the clear top four candidates.