Question

Where did many of Roosevelt’s New Deal ideas come from originally?

Answer 1

The Populist Party.

The People's Party (its official name) was commonly known as the Populist Party or simply the Populists.  The party was formed in 1891 and existed till 1908.  Its strongest period of influence was from 1892 to 1896.  It merged into the Democratic Party in 1896, though a small portion of the group retained its active, independent status till 1908.  The Populists original base of support came mainly from farmers, and then they allied also with the labor movement in the USA. 

The New Deal policies put into place by the Roosevelt administration in the 1930s echoed the issues and demands the Populist Party previously had emphasized.