Yeah, especially since the effect is only 15%. It also seems possible that public sentiment was already shifting, which caused the party to shift, which influen

Yeah, especially since the effect is only 15%. It also seems possible that public sentiment was already shifting, which caused the party to shift, which influenced the undecided 15%. For example, if you look back now in the US, you could probably find that some Democrats started supporting gay marriage after the party changed its stance. It's also the case that the party changed its stance in the middle of a large scale shift in public opinion that was occurring.