Research calls are exempt from TPS so political organisations might be able to get away with calling you if they position their phone calls as research.
Back in the US, many political campaigns have had hard times calling me.
Ahh...especially at dinner time...
Telemarketer: "Can we count on you to vote for (Joe) this election?"
Me: "Not anymore. You called me, someone not affiliated with your party*, while I was eating dinner. (Joe) just lost the chance for my vote. Thank you and your welcome." (hang up)
I never got a call again from them. Junk mail, on the other hand, increased. Oh, and I also do similar things with Mormons, Hare Krishnas, Jehovah's Witnesses, and other proselytizers...except that I have a few degrees in comparative religion, so I have more fun with these folks. I once tried to convince Mormons that I was trying my hardest for a good suicide (as a really bad reading of Jainism as if they'd know!).
* I know this is a fact since I am not registered with any political party.