Hello! For the first Common App essay prompt, I wanted to write about my interest in politics. I was planning on telling the story of when I canvassed for a presidential candidate in the primary election, but I don’t know how in depth I should talk about the specific policies. I wanted to discuss why the candidate’s policies are important to me and how they motivate me to effect change, however, I do not want to potentially turn off an admissions officer who may not agree with my political stance. I would appreciate any tips on how to approach this topic. Thank you! 
Most years you would be okay. This year… not as sure. And it depends on the school and which candidate. Can you write about what motivates you and specific anecdotes without stating the candidate or even the issue? They want to know how you think, how you act and react, how you learn, how you form your view of the world. They don’t so much care which policies or positions you take – so you don’t necessarily have to be specific.
If people are willing to end multiple-year friendships over politics (I’ve seen it!), they could certainly feel strongly enough about specific policies to let it color their opinion of you as an applicant.
IMO the common application essay is too short to delve into specific policies…keep the focus on you.
You don’t have to write about goal at all if you don’t want to. Some of the best essays turn on small events or small character traits that are unique to you. You want them to say, "Hey, that is the kid that " when they are talking about you at the admissions meetings. You don’t want to be boring, trite, cliché, or vague (or vulgar, for that matter). You want to have something that sparks their interest about you and makes you stand out.
No, you should not write about politics in your essay. Writing about a volunteering experience in your local community is a great topic, but not politics.