Donating design experience for 2018 candidates

I've donated money, called for candidates, collected signatures, hosted campaign fundraisers, called, faxed and emailed every single rep I can think of for every single issue that has come up and I'm still wracking my brain how I can contribute for the upcoming Blue Wave.

I used to do graphic design for a living, and I was thinking that I could donate my services to candidates. Is that something I can just contact candidates and offer, or do I have to have a business or non-profit set up to be able to do that? Anyone know?