If someone uses children against space advocates, whether or not the comparison makes sense, we'll lose. Assume none of the candidates knows diddly about space. It's a good assumption. If it's wrong, we'll be pleasantly surprised. If you're going to convince one of them to make space an issue, you need to tie it to issues they DO understand, and which have a history of moving the American people.
Candidates have themes.
If you're selling to Al Gore, sell it as reinventing government. If you're selling it to Pat Buchanan, sell it as American competitiveness. Be ready to do a lot of writing, a lot of talking to staffers, and answer a lot of questions. If you're targeting a candidate, wrote an op-ed piece in a newspaper that shows how that's candidate's campaign theme fits your ideas. The campaign will probably contact you.