Maybe lobbying and the current rules about campaign finance are undemocratic and should be changed, but meantime where's the lobbying group where we can donate

Maybe lobbying and the current rules about campaign finance are undemocratic and should be changed, but meantime where's the lobbying group where we can donate to advocate for tax simplification? I used to think it was Americans for Tax Reform, now I think Tax Policy Center is the closest thing, but while Bankman has worked a lot with them in the past, in this article they seem at least ambivalent if not opposed to it. Any other suggestions of which nonprofit lobbying organizations can be used to offset the impact of Americans for Tax Reform, Intuit, and other organizations who favor tax complexification?