'I pledge that I won't vote for any Republican at any level-- from dogcatcher or state legislator right on up to the presidency-- until the Republican party acknowledges the reality of man-made climate change and makes a serious proposal to deal with it.'
If we could get 4-5 million people to sign this, the Republicans would sit up and take notice. And if we could get 10 or 20 million people to sign it, they would in fact start losing elections, at all levels -- even ones they would otherwise have won.
This would also have the effect of moving this issue to the fore in our national politics. Although polls now show a solid majority believe climate change is happening, we're causing it, and we should do something about it, it still polls at or near the bottom of people's priorities. This could change that.