Via: https://thinkprogress.org/al-gore-dont-vote-third-party-15711ce062e7
Al Gore was asked what he would say to voters concerned about climate change but dissatisfied with both major candidates and considering voting for a third party, such as the Green Party. Gore replied:
First of all I understand their feelings and misgivings. But if they are interested in my personal advice. I am voting for Hillary Clinton. I urge everyone else to do the same.
I particularly urge anyone who is concerned about the climate crisis, sees it as the kind of priority that I see it as, to look at the sharp contrast between the solar plan that Secretary Clinton has put forward, and her stated commitment to support the Clean Power Plan, and the contrast between what she has said and is proposing with the statements of the Republican nominee, which give me great concern.