To really understand how a place works, first you have to speak the language.
A special Committee session where members review, debate, and amend a bill before a vote to pass it out of Committee, a markup is the first major hurdle a bill faces on its way to becoming a law. Markups are time-consuming and have strict attendance requirements, so Committee Chairs only schedule them for bills they are willing to invest in-- bills which have a good chance of passing. Once a Committee reports out a bill the Majority Leader decides whether or not to bring it up for the entire Senate to debate, amend, and potentially pass.
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