The Oregon Constitution is easier to amend than its federal counterpart. Amending the U.S. Constitution requires a two-thirds vote in Congress and ratification by three-fourths of the states. In Oregon, once an initiative amendment to its constitution has been placed on the ballot by initiative petition, or once a legislative amendment has been referred to the people by a simple majority vote in the state legislature, a simple majority of favorable votes is enough to ratify it. Placing a petition for an amendment on the ballot requires a number of valid signatures of registered voters equal to eight percent of the total number of votes cast in the last gubernatorial election, higher than the six percent required for a change in statute. See the list of Oregon ballot measures for initiative amendments.