Ask HN: Why not tax campaign donations?

I think we all agree that the amount of money in politics is a very serious problem and is essentially turning this country into a kleptocracy. But on the other hand, if you can spend tens of millions of dollars on ads saying "Taylor Swift is amazing, you should listen to her," why shouldn't you be able to do the same for someone like, idk, Elizabeth Warren.

My idea would be to give every person a tax credit of ~$100-300 that they can use to donate to a campaign or Super PAC. Any other donations those organizations receive gets taxed at ~70%. I think that should remove most of the special interest money in politics while preserving free speech.