It was a long time ago that I have looked into this. My understanding from the political science is that countries where farmers votes aren't as important, also have far less subsidizes.
Groups that already have subsidizes are better at defending them. Even if in absolute terms their numbers aren't as big.
They are totally going to defend themselves, mainly through boycotts, barricades and varying degrees of riots. That can totally cause a vote issue, but it's because the rest of the population is pissed off by the road blocks etc