Biden and Sanders may be too old in 2020 to hold up to the rigors of a presidential campaign. Booker seems too close to big business and establishment Washington for my taste but i guess the climate of 2020 may fair better for beltway insiders than the last cycle.  My support is with Warren.  She is a tried and true progressive whose message can reach out to many of the Obama voters who either stayed home or went for Trump in 2016.