The Congress can propose a constitutional amendment, if it is passed by a two-thirds majority in both houses. In order to be ratified,three quarters of the state legislatures then have to approve the amendment.
Over 11,700 amendments to the constitution have been proposed since 1789 in Congress. Almost all of them have died in committee. Some have made it out of committee but only 33 of them have passed Congress and gone on to the states for ratification. Of those only 27 have been ratified by the states and become part of the constitution. Since the beginning of the 20th century the Congess has put an eight year cap on the time that states can ratify an amendment. Two amendments have failed to be ratified, DC representation and equal rights, while he others are technically open for future ratification.