Populism on both the left and right of the political spectrum have been rising in recent years, as it did after the Great Depression. (See Silvio Berlusgoni, Donald Trump, and Toronto's Rob Ford)
When times are tough, the tendency for all of us is to forget about our "Fellow Man", and to start looking out for ourselves and our kin. Populism exploits our anxiety for our own current survival at the expense of others ("Stop immigrants, they're stealing our jobs"; "cut welfare, we just can't afford feeding other people when we don't have enough for ourselves"; etc., etc.). We become mean without realizing it.
The irony is that by taking away the safety beneath the Other, we are unconsciously knocking out the foundation under ourselves, too.
I don't know how to stop this. I get that feeling sometimes, too. All I can say is: Take a breath, from time to time, and before you decide who to cast your ballot for, take a moment to ask, "Is this vote good for other people?" instead of "What do I get?"