I suggest writing down limits to how much news you can watch and read on TV, newspapers, and online. Write down the hours (something reasonable like two hours per day) on a notecard, and tape it to the TV (or computer). If you buy news magazines or newspapers, restrict them from your possession at all times, or throw them away after reading it for one and only one time, once a day (preferably in the morning).

Replace your "Political Blackout Time" with goal directed activity, such as leaving your residence and exercising, spending time with friends, or exploring new hobbies you have always thought of doing or that seem interesting. It's important to replace the obsession with something else, or you will experience anxiety and it will be hard to overcome the desire to "reoffend". If you've never tried psychotherapy with a psychologist for these sorts of problems, I highly recommend it.

Last but not least, be good to yourself if you should happen to slip up from time to time; it isn't a personal failure if you give in and slip up now and then. If you do resort back to old habits, as soon as you recognize it, physically stop yourself and remove yourself from the content. Go for a walk, ride a bike, socialize, do a hobby, read a fiction novel, whatever. You can assign a trusted person to be accountable to, who is someone you can call whenever you are in danger of resorting to the obsessional behavior (sorta like an AA Sponsor).

Hope my ideas give you a starting point.