I’m not sure that party affiliation has anything to do with the level of corruption. I would imagine that corruption tracks far more closely to regional GDP - more money, more backroom deals.
I agree that more money probably means more backroom deals. This seems simple to me: One party wants to regulate, the other de-regulate. Which of those platforms attracts the most money?
So some democrat can make it his core issue to stop corruption and the people can vote for him/her.