The simple answer is - Everyone. Every modern country embraces some level of socialism.
Socialism is Working-class Politics
You are if you work.
48% Want a Socialist President
In a true capitalist economy, there would be no public schools,
no state owned roads and highways, no public works, no unemployment insurance,
no workers' compensation, and no Social Security benefits etc.
These are all socialized services.
No one is truly free in a capitalist society.
The ideologies of liberal democracy only serve to legitimate what is in fact a system of freedom and democracy only for some. The political equality emphasized by liberals is but a veil for the economic inequality that is so fundamental to a capitalist society and so detrimental to human freedom.
Socialism improves social progress while capitalism erodes it.
Socialism is the well-settled conclusion of a society that values democracy. Americans cherish democracy. Despite America's violent acquisition of indigenous land and America's coercive leveraging of black slaves as financial instruments, the egalitarian image of our Constitution is still an idea worthy of perennial refinement into American laws, practices, and governance.
Capitalism oppresses people with under-employment and low-wages. Socialism, on the other hand, restricts those who have been placed in position of trust from using their positions to oppress others. Or another way of putting it – Socialism oppresses the capitalist's ability to oppress the workforce.
If you work and want fair wages, then you are a socialist.
When a capitalist tries to argue that socialism subsidizes the cost of living of citizens that are unable to work, point out the fact that – The lives of wealthy capitalists are actually subsidized by the hard work and sweat of low-wage workers.
Socialist policies grew America's middle-class; but, our current capitalist policies are destroying the Middle-class. Each era of increased capitalism led to a financial crisis. Every time socialism is increased, an era of historic economic prosperity begins.
Defining Capitalism, Socialism, Communism & Fascism
Caveat: There are some inherent pitfalls trying to offer simple, bite sized definitions of capitalism, socialism, communism and fascism.
For a point of reference, the United States is a Constitutional Democratic Republic that has long embraced both capitalism (free markets) and socialism (public schools and universities, and public works – parks, roads and highways, sewer and water, dams, harbors, as well as social welfare, such as worker’s comp, unemployment insurance, social security etc.).