Red button pressers, would you change your vote if...
Red winning meant the people who pressed red had to be the ones to carry out the culling of Blue button pressers? The selection of who has to carry it out being purely at random with good odds that you will have to kill a stranger if the vote is close and good odds that you don't have to if the vote isn't.
Logically nothing else changes. The blue voters are subdued and no threat to you. You are allowed to use any method you want so long as it involves you actively handling it yourself. Nobody but yourself will know if you had to do it or who you did it to. But you cannot back out.
(this isn't meant to be a gotcha or way to indirectly call anyone murderers, I'm just curious on how it would or would not change people's decision making despite having the same exact outcome as it pertains to people living and dying)