Washington Post: What to know about tonight’s Democratic debate

(COMBO) This combination of pictures created on Dec. 5, 2019 shows in this file photo taken on Nov. 20, 2019 Democratic presidential hopeful Vermont Senator Bernie Sanders participates in the fifth Democratic primary debate of the 2020 presidential campaign season co-hosted by MSNBC and The Washington Post at Tyler Perry Studios in Atlanta, Georgia, in this file photo taken on Nov. 20, 2019 Democratic presidential hopeful Massachusetts Senator Elizabeth Warren speaks during the fifth Democratic primary debate of the 2020 presidential campaign season co-hosted by MSNBC and The Washington Post at Tyler Perry Studios in Atlanta, Georgia, in this file photo taken on Nov. 20, 2019 Democratic presidential hopeful Minnesota Senator Amy Klobuchar speaks during the fifth Democratic primary debate of the 2020 presidential campaign season co-hosted by MSNBC and The Washington Post at Tyler Perry Studios in Atlanta, Georgia, in this file photo taken on Oct. 28, 2019, Democratic presidential candidate Senator Michael Bennet (D-CO) arrives to speak during the 2019 J Street National Conference at the Walter E. Washington Convention Center in Washington, DC, in this file photo taken on March 23, 2017, a view of the Capitol dome is seen on Capitol, in this file photo taken on Oct. 10, 2019 Democratic presidential hopeful New Jersey Senator Cory Booker reacts during a town hall devoted to LGBTQ issues hosted by CNN and the Human rights Campaign Foundation at The Novo in Los Angeles.