There's a double standard that I see a lot here, where people want to vote for a party, denigrate those who chose not to participate as being morally culpable for the results of the election, but won't take moral culpability for what their team does when they're in power.
If you vote for team A and they win and then do something bad (inevitable), shouldn't you be morally responsible for that? After all, you seem fine claiming non-participants have moral culpability for whatever the winning team does.
Yes, you are, to the extent that "the other option" would have been better.
This seems incredibly obvious. If my options are "don't bomb children" and "bomb children", there's an obvious choice and obvious culpability. If my options are "bomb children" and "bomb way the fuck more children" the choice is also obvious.
You do not get to pretend a moral dilemna doesn't exist just because you're not a fan of the available choices. You are still culpable.
Consider this scenario:
You have a train hurtling down the track that forks into two groups of people, 10 in one and 5 in the other, some of the people go on to cure cancer and some are murderers and you don't know where they are. Also it's possible batman set up the scenario to kill the bad guys and by flipping the switch you kill the good guys. Or the Joker set it up and the reverse is true.
In this case, you could argue that you only have moral culpability by intervening. Unless you are absolutely sure you have full knowledge of the intended consequences by acting, you can absolve yourself of the moral culpability by non-intervention.
And since we don't know the long term consequences of political actions, there is at least an argument for non-intervention.