See here [EA · GW] and here [EA · GW] for my attempts to do this a few years ago! Our project (which we called Pact) ultimately died, mostly because it was no one's first priority to make it happen. About once a year I get contacted by some person or group who's trying to do the same thing, asking about the lessons we learned.

I think it's a great idea -- at least in theory -- and I wish them the best of luck!

(For anyone who's inclined toward mechanism design and is interested in some of my thoughts around incentives for donors on such a platform, I wrote about that on my blog five years ago.)

A very similar project called "Repledge" launched in 2012, but then fizzled. I don't know why. But you might try to track down their story and learn from their fail if you want to make this project succeed.

https://web.archive.org/web/20120415055024/http://www.repledge.com/

seems like an interesting idea. I had never heard of it before, and I'm generally decently aware of weird stuff like this, so they probably need to put more effort into publicity. I don't know if truly broad public appeal will ever happen but I could imagine this being pretty popular among the kinds of people who would e.g use manifold.

one perverse incentive this scheme creates is that if you think other charity is better than political donations, you are incentivized to donate to the party with less in its pool, and you get a 1:1 match for free, at the expense of people who wanted to support a candidate.

also, in the grand scheme of things, the amount of money in politics isn't that big, but it's still a solid chunk. but the TAM is inherently quite limited.

https://slatestarcodex.com/2019/09/18/too-much-dark-money-in-almonds/

One downside of this is that charitable donations are typically tax deductable, but political donations aren't. Whether this matters depends on tax brackets and whether the donater is going to itemize, but I imagine it would make it harder to convince people.

This doesn't work as advertised.

If I care about the election more than other charities, I won't give to such a fund. My dollars will do more towards the campaign on average if I give directly to my side. This effect is trivial if the double impact group is small but very large if it is most donations.

In an extreme case, suppose that most people give to double impact and the two campaigns are tied $1b - $1b. One donor gives their $1m directly to their side. It is the only money actually spent on advertising; that side has a large advantage in ratio of funds spent.

More realistic scenarios yield smaller average ratios, but always less expected return for your preferred campaign if you give to it vs, double impact.

One issue is that $10m of ads for one party and $8m in ads for the other is not equivalent to $2m in just one, as most ads aren’t for getting people to switch sides, but to just attend at all.