Bill de Blasio

The highlights: The 58-year-old second-term mayor of New York City was born in Manhattan and previously served as the city's public advocate and on the City Council.  

The issues:
• Has not released proposals as a presidential candidate.
• Signature achievements as mayor include implementing universal pre-K in New York City; expanding paid sick leave; raising the minimum wage.
• Has called for higher taxes on the rich.

Tim Ryan

The highlights: The 45-year-old U.S. representative from Ohio, serving his eighth term in Congress, has written several books, including one about mindfulness.

The issues:
• Combat climate change, recommit the United States to the Paris Climate Agreement.
• Reform the education system to include "social and emotional learning" in classrooms.
• Implement Medicare for All, reform access to health care for veterans and reduce veteran suicides.