espouse vs speak for

espouse

verb
  • To accept, support, or take on as one’s own (an idea or a cause). 

  • To become/get married to. 

speak for

verb
  • To speak on somebody's behalf. 

  • To represent an intrinsic quality 

  • Used other than figuratively or idiomatically: see speak, for. 

  • To claim, reserve, or occupy. 

How often have the words espouse and speak for occurred in a corpus of books? (source: Google Ngram Viewer )