A Senator is able to use a filibuster in order to prevent a bill he /she dislikes from becoming law if a majority of his/her colleagues support it.
A filibuster in the United States Senate is a political strategy in which a senator speaks in order to prevent a measure from being brought to a vote. It is a dilatory tactic by which senators engage in extended debates as an attempt to delay or block a vote on a bill. The Senate rules allow a senator to make of a filibuster unless two-thirds of the Senators vote to invoke “cloture,” which is an official closure to debate.