Actually, during one of Ryan Murphy's first Twitter Q&A's someone talked about how great it would be if Klaine sang "Come What May". Murphy responded that it was a great idea and the fandom went nuts over the idea. Whether Chris campaigned for it IDK, but I can say it wasn't performed solely based on his passion for the song.
Chris had been campaigning for CWM for years - remember this? This was way before Ryan teased fandom about it.
Chris used to be Ryan’s golden boy - he wrote Kurt based on his own life. I never said it was “soley” because of Chris, but I’m sure Chris had a HUGE influence over CWM being sung by Kurt & Blaine.