Candidates in the race, senator Elizabeth Warren. Just on monday warren said sanders told her back at a meeting between the two of them in december of 18 that he didnt believe a woman could win the presidency in 2020. Senator sanders has since called that claim ludicrous. Cnns Arlette Saenz is there at the debate site. Big picture, first of all, what are you watching for tonight . Reporter well, brooke, were going to have six of the democratic contenders on the debate stage here in des moines, iowa, as were 20 days out from the caucuses. These candidates are really heading into crunch time trying to make their case for why they should be the democratic nominee. The host of issues are really going to be at the forefront tonight. Youre going to have impeachment, Foreign Policy, the always continuing debate over health care for democrats but also youve seen these tensions that have been brewing over the past really 48 hours between Bernie Sanders and Elizabeth Warren. And as you mentioned