The Overton window is an approach to identifying which ideas define the domain of acceptability for a democracy's possible government policies. Politicians can only act within the acceptable range. Shifting the Overton Window involves proponents of policies outside the window persuading the public to move and/or expand it. Proponents of current policies, or similar ones, within the window seek to convince people that policies outside it should be deemed unacceptable.
You know how we all sneer when Trump rants and raves about how he's "bringing the troops home," and then just turns around and sticks them in Saudi Arabia and Iraq? That's exactly what we should be doing when Bernie rants and raves about the plight of the global poor and then turns around and says we need strong borders to keep them out.
When Obama blathered on about peace, but illegally invaded two additional countries, we should have mocked him. When Clinton had the audacity to talk about gay rights after a lifetime of crusading against the LGBTQ community, we should have given her nothing but derision. Don't let these pieces of shit, who wield all the power in the world, get away with outright evil simply because they've borrowed a few progressive catchphrases or pay lip service to humanitarian ideals.
By all means, vote for who you must to get Trump out of office, but start shifting the window. Make it clear that you're not going to be like the Democrats of the Obama era, who went from being stridently anti-war and pro-immigrant to cheering for Obama when he shouted down a transgender immigrant calling him out on his heinous deportation policies, or when he said awful shit like "turns out I'm really good at killing people" after killing a 16 year old boy in a drone strike.
