JOHNSTON, Iowa — A proposed constitutional amendment banning gay marriage in Iowa will again be a topic during the legislative session beginning Jan. 9, but the top Senate Democrat said Thursday he would block debate over the issue.

"People's rights should not be put to a popular vote," said Senate Majority Leader Michael Gronstal, D-Council Bluffs. "We didn't put slavery to a vote of the people. We didn't put the right to go to a school in your neighborhood to a vote of the people of Iowa."

Senate Minority Leader Jerry Behn, R-Boone, said the debate is less about gay marriage than allowing voters to have their say on an emotional issue. He promised that Republicans will again push the issue.

"We're just discussing should Iowans get a vote on it," said Behn. "Absolutely, Iowans should get a vote on it. It's outrageous that he's going to say no."

The two spoke during a taping of the Iowa Public Television program, "Iowa Press."

Senate rules and tradition give the majority leader absolute authority over what issues are debated in the chamber. Democrats held on to their slender 26-24 majority by winning a special Senate election last week and there's been no challenge to Gronstal's leadership role.

The state Supreme Court in 2009 struck down a state law defining marriage as being between one man and one woman, and critics of that decision have sought to amend the state's constitution to overturn that decision. Amending the constitution is a deliberately arduous task. A resolution must be approved by two consecutive General Assemblies, and then put to a vote of the people in a statewide election.

The Republican-controlled House has already approved such a resolution, but Gronstal has blocked Senate debate. If he succeeds again, the resolution would have to be approved by the Legislature elected in 2012, and again by the Legislature elected in 2014.