Only a small share of introduced legislation is ever voted on by a full chamber. The point at which most of it stops is the committee stage, and the mechanism is scheduling rather than defeat. Procedures differ between jurisdictions and change over time.
Referral decides the terrain
A bill is assigned to one or more committees according to its subject matter, and that assignment is made by the presiding officer or the clerk applying the chamber's rules.
Which committee receives it matters a great deal, because committees differ in composition, workload and appetite for a given subject.
A bill touching several areas can be referred to more than one, and each referral is another body whose agreement is required before it can move.
The chair controls the calendar
Committees act on what is scheduled, and scheduling is generally the chair's prerogative. A bill that is never placed on an agenda is never debated or voted on.
No formal rejection is required for this. The bill simply remains where it was referred until the legislative session ends and it expires with everything else unfinished.
That is why sponsors describe bills as dying in committee. The verb is accurate, because nothing happened rather than because something was decided.
Hearings are the first real test
If a hearing is granted, the committee takes evidence from officials, affected parties and specialists, which establishes a record and exposes weaknesses in the drafting.
A hearing is not the same as a vote, and many bills receive one and go no further, having served to air an issue rather than to advance a text.
The record produced at that stage is nonetheless durable, and it is frequently reused when a similar proposal returns in a later session.
Markup can rewrite the text entirely
When a committee does proceed, it works through the bill section by section and votes on amendments, a process capable of changing the substance beyond recognition.
Sponsors accept amendments they dislike in order to secure the votes needed to report the bill out, so the version that emerges reflects the committee's balance.
A bill reported without recommendation still moves forward, which is a signal that the committee is unwilling to endorse it but unwilling to bury it either.
Routes around a committee are deliberately hard
Most chambers provide a mechanism for the membership to force a bill out of committee against the chair's wishes, but the thresholds are set high on purpose.
Using such a procedure requires members to act against their own leadership publicly, which carries costs in a body that depends on repeated cooperation.
The result is that the committee gate holds in the overwhelming majority of cases, and controlling committee assignments is one of the most consequential powers in any legislature.