Voters don't really choose a representative. They are given choices. Two choices, of which, let's face it, most people will just pick whichever one is on "their side". Those choices are created by outside forces. And those choices, once chosen, will do... whatever the hell they want. There's no consequence to them doing whatever the hell they want. So it doesn't really matter what the choice is to begin with. You're as likely to get what you want by praying to the Flying Spaghetti Monster as by voting. The "choices" are just gonna do whatever the hell they want anyway. Whether you get what you want or not is incidental.
But let's assume you do hold somebody responsible for choosing something they have no control over. What does that mean to "hold them responsible" ? You gonna actually do something? Throw them in jail? Kill them? Probably not. You're probably just gonna say nasty things about them on Facebook. Which you could do at any time, for any reason. So who gives a shit what the argument is? It makes no difference to anything at all. You might as well ask for a valid argument for why the sky is blue. Ain't gonna change the sky.