DENVER -- The Secretary of State's office has received 133,000 voter signatures for a constitutional amendment defining marriage as a union between one man and one woman, and yet more than 100,000 other people also signed a petition to ensure that domestic partnerships are recognized.

State law already defines marriage as a union between one man and one woman but the proposal by Coloradans for Marriage would add it to the state constitution, where it would be tougher to change.

Meanwhile, a group called Coloradans For Fairness wants to create an amendment allowing domestic partnerships. The group is also supporting a referendum that would change state law to recognize domestic partnerships.

Monday was the deadline for proponents to submit voter signatures to the secretary of state to get measures before the voters in November. Each group needs about 68,000 verified signatures of registered Colorado voters to win a slot on the ballot.

At least 18 measures could go before voters, including four on gay marriage and one legalizing possession of small amounts of marijuana statewide.

Seven measures were placed on the ballot by lawmakers. They range from directing the attorney general to sue the federal government to demand enforcement of immigration laws to requiring school districts to spend at least 65 percent of their operational budget on "services that directly affect student achievement."