I did not find any other nonprofit organization with your website name, and I did not see any website that resembled your site or its content. But, admittedly, my search was a brief one.
I did run across many uses of the words "party foul" (the words in your web title), but none were used in a way that would confuse consumers into thinking there was a connection between these and your political website and its forum.
What IS protectable about your website is the media incorporated and displayed on the site (the text, artwork, photos, music or other sound, movies or other animation). For anyone to take and use this media (the part of your website that contains copyrightable expression) without your permission, then that could potentially be an infringement on your rights.
Copyright protection does not extend, however, to a website's layout or site design, so if the other site merely resembles yours but does not use any of your copyright-protected material, there is not much you can do about it. And copyright protection does not extend to the idea of a political website with forum, so there is not much you can do about that.
So, from this distance and without locating the other website that concerns you, I cannot tell you if there is any lawsuit you could pursue with success. For a thorough, personal review of all of the facts, and a side-by-side comparison of your site to the one you feel is copying yours, you will probably have to consult with an attorney in your area.
Good luck, Greggd09.