What is an effect of a successful filibuster?

A successful filibuster can effectively kill a bill, even if there is majority support for it. A filibuster is a tactic used most commonly in the U.S. Senate where a senator or a group of senators speaks for an extended period to delay or block a vote on a proposed piece of legislation. This means that if a filibuster is in place and a supermajority of 60 votes is not reached to close debate – known as invoking cloture – the bill cannot proceed to a vote, regardless of the support it might have among the majority of senators.

This unique aspect of the legislative process highlights the power of a minority in some situations, as it can hinder the passage of laws that may have widespread agreement among the majority. It showcases the importance of negotiation and compromise in the Senate, as the threat of a filibuster can motivate the majority party to seek bipartisan support or make concessions to ensure the bill's passage.

The other choices do not accurately describe the effect of a successful filibuster. It does not guarantee that a bill will be passed, nor does it speed up legislative procedures or specifically allow for more amendments. Instead, a successful filibuster serves to prolong debate and effectively stymie legislative action.