The methods of formal amendment are ways that article V of the Constitution stipulates that the Constitution of the United States can be amended. Either a proposed amendment must pass both the House of Representatives and the Senate with a two-thirds majority vote or a constitutional convention must be called by a vote of two-thirds of the state legislatures. Afterwards, the amendment must be ratified by three-quarters of the states.
As of early 2014, all of the constitutional amendments successfully ratified have been proposed by Congress. A constitutional convention of the states has never been convened. Though thousands of proposals for amendments have been made, only 27 amendments have survived the ratification process and become part of the Constitution.
The President does not have a part in the process of amending the Constitution, so once an amendment passes Congress, the National Archives and Records Administration's Office of the Federal Register sends information packages to each state along with a notification letter to each governor. Typically, the state ratification process has a time limit set by Congress. Though a specific period of time is not set forth in the Constitution, the Supreme Court has stated that the ratification process must be completed within a reasonable amount of time. In the case of several past amendments, the time period has been seven years.