Starting in the 1970's the filibuster, began to be used in the senate by both parties as a means to prevent a vote that would be won by a simple majority. This tactic allows 41 Senators to block passage of a bill, and over time this has become the rule for all major decisions resulting in gridlock at the will of a minority.
During the debate over ratification of the US Constitution Alexander Hamilton saw the danger of this and described it in one of his contributions to The Federalist Papers, a series of articles in support of ratification of the proposed US Constitution. Here's an excerpt from Federalist 22;
"... what at first sight may seem a remedy, is, in reality, a poison. To give a minority a negative upon the majority (which is always the case where more than a majority is requisite to a decision), is, in its tendency, to subject the sense of the greater number to that of the lesser. ... If a pertinacious minority can control the opinion of a majority, respecting the best mode of conducting it, the majority, in order that something may be done, must conform to the views of the minority; and thus the sense of the smaller number will overrule that of the greater, and give a tone to the national proceedings. Hence, tedious delays; continual negotiation and intrigue; contemptible compromises of the public good. And yet, in such a system, it is even happy when such compromises can take place: for upon some occasions things will not admit of accommodation; and then the measures of government must be injuriously suspended, or fatally defeated. It is often, by the impracticability of obtaining the concurrence of the necessary number of votes, kept in a state of inaction. Its situation must always savor of weakness, sometimes border upon anarchy."
Hamilton's prediction seems prescient given recent events.