You can find the brief of the Indiana Democratic Party here.
I will post the ACLU brief when I receive permission to post it. UPDATE: It is here.
Under new Supreme Court rules, amicus briefs are due 7 days after the merits brief for the side one is supporting (or after the petitioner’s brief if neither side is supported). I’ll be linking to amicus briefs in coming days, including one I’m working on right now.