Political opponents of Vermont Senator and Democratic presidential candidate Bernie Sanders often label him a socialist. However, Bernie Sanders considers himself a "democratic socialist," although he still acknowledges capitalism should play an important role in society. At the first 2015 Democratic Presidential Debate, Sanders offered the example of Denmark--which has high taxes, expansive government healthcare and welfare programs, but also significant private investment--as a society the United States should emulate.
Whether or not you believe it would be bad to have a socialist (or a democratic socialist such as Bernie Sanders) in the White House depends on the political philosophy to which you ascribe. If you support a robust governmental healthcare and welfare sector, you might be inclined to support a candidate such as Sanders. If you generally oppose government involvement in healthcare and welfare, you might be inclined to oppose Sanders.