I'm happy to pledge (assuming I agree with the goals of the charity - a few international ones would be nice. I'm not sure that health care (Mayo clinic) is a charitable matter for most western countries other than the US - I'm happy to support them outside the US in Africa/Asia - the richest country in the world ought to be able to provide health care to it's own people) .
Not all of us are Americans, and I'm not sure I want to help American politicians deal with their own failings via charity -

EDIT though the same could be said of African politicians - people are suffering because of the failings of politicians everywhere - so I change my mind. Any charity will do.