Final answer:
The Senate's primary defense against a filibuster is the cloture rule, which requires a super majority of 60 votes to invoke. Exceptions to the cloture rule exist for certain types of legislation.
Step-by-step explanation:
The Senate's primary defense against a filibuster is the cloture rule. Cloture is a parliamentary procedure that allows the Senate to end a filibuster and proceed to a vote on a bill. In order to invoke cloture, a super majority of 60 votes is required.
For example, if senators are filibustering a bill and the majority party wants to end the debate and move forward, they can call for a cloture vote. If at least 60 senators vote in favor of cloture, the filibuster is broken and the bill can proceed to a vote.
However, it's worth noting that there are certain exceptions to the cloture rule. Filibusters are not permitted on the annual budget reconciliation act, and for judicial nominations, only 51 votes are needed to invoke cloture.