There's an opinion column in the Washington Post by David Byler titled "Politicians probably don't need your money." The gist is, once a candidate has enough money, more won't make a difference, and it's true. What does make a difference is contributing to grassroots organizations. If you're a U.S. citizen, may I recommend Blue Tent? Blue Tent tells you the most effective way to use your money, routing your contribution to the people who will put it to good use. https://bluetent.us/