You got it backwards. In fact FDR campaigned against Hoover's deficit spending.
Once in office, FDR reversed course and doubled-down on Hoover's approach.
Hoover and FDR shared a belief that excess production was the problem - that's why both pushed govt programs to restrict it. That's what put the "Great" in "Great Depression". (Previous panics didn't last nearly as long.) FDR didn't back off until the approaching WWII made it obvious that an "Arsenal of Democracy" had to actually produce massive amounts of stuff.
FWIW, Congressional Repubs at the time voted overwhelmingly for Social Security.