Would you call him a socialist instead?
No.
I think he, like most US mainstream politicians, have their base in liberalism.
Bush did too, Clinton, Reagan, Carter, Nixon, Kennedy, Truman, et al.
Some are leaning towards social-conservative, some towards social-liberalism.
Traditionally, the Republican party has been pro free-trade, so that makes them more true to liberalism in that sense.
At the same time, Democrats have supported abortion rights, been more liberal on recreational drugs, not as social-conservative. And that is also being liberal.
So both parties have areas where they are liberal - and some areas where they're not.
But short answer is that all mainstream politicians today are liberals to some degree.
Because liberalism is what our democracy is funded on.