You run an interest group with one goal: get your bill through both chambers of Congress before the session ends. Persuasion costs Political Capital, and a rival interest group is spending theirs to stop you.
Congress needs a majority in the House (218 of 435) and the Senate (51 of 100) to send a bill to become law. Every representative belongs to an ideological bloc that starts undecided. You and a rival interest group both compete to win them over before the session's rounds run out.
Some reps already agree with you (or the rival) before a single meeting happens: a bill that fits an ideology strongly enough locks in automatic day-one support on both sides.
Each round you receive PC from dues, fundraising, and momentum. Spend it on lobbying tactics: the further a bloc is from your cause, the more it costs to move them.
At the start of each week (round), a newspaper pops up with that week's headlines: endorsements, scandals, polls, and ad campaigns that can swing blocs your way or against you. You'll need to read it before you can act.
A chamber is passed once you reach its majority. It's blocked if the rival locks up enough votes that you can no longer mathematically reach majority. Pass both chambers to sign your bill into law.
Choose the legislation your coalition will champion this session.