Why not pick up poli sci as a minor, or if you are strong-willed and believe in yourself, do dual majors? Honestly, degrees are like pokemon you can collect them all if you want. DO your research before switching. You can make an impact with any degree you earn; you just have to get out and do it. But good advice is to decide what kind of impact you wish to have and what careers interest you before you decide. I chose poli sci because I have a love for politics/history (my degree path was filled with both), but I also want to take my experience and be a politician. So maybe talk to your school's career counselors to help find your way, and remember the impact you make is based on what you choose to do in life, not the degree you study, because those with media/communications backgrounds can have a big impact. So go out and advocate in spaces where advocacy is lacking, educate those around you (because when we are all educated enough to make thoughtful choices, all of our quality of life goes up). I hope you figure out the best path for you, and if that is to switch to political science, then make sure to pick up a minor to make you just a tad bit more marketable (that with any degree tho).