This concentrated effort on Capitol Hill underscores Harris's strategy to rapidly advance her presidential campaign following Biden's unexpected withdrawal from the race amidst mounting pressure after a contentious debate performance last month.
He said Harris cares deeply about democratic issues like protecting a woman's right to choose or protecting workers rights and creating economic opportunities.
US Representative Nancy Pelosi has called Biden a "patriotic American" who has always put US first and expressed gratitude to him for always believing in the promise of America.
The process of selecting a new nominee remains uncertain, but an increasing number of Democrats believe that any transition would likely culminate swiftly with Harris assuming the mantle.