Answer:
Private citizens have a duty to help the poor as long as they can, in the form of charity. In fact, the United States is the most charitable country in the world, with American citizens collectively giving 2% of annual U.S. GDP to charity.
However, when private charity is not enough to cover the basic needs of those in most need, the government has the duty to step in and use the power that it has to redistribute some of the wealth of society, in order to fund social programs that allow the poorest and the least fortunate to survive, and to lead a life with basic dignity and liberty.