State law already prohibits same-sex marriage, but supporters of the amendment are making the argument that without being enshrined in the constitution, the courts could end up overturning the law.
But even if the proposal clears the full Senate, it will likely go nowhere in the Democrat-controlled House.
The House and Senate approved a similar amendment in 2006. But the amendment stalled on its required second trip through the legislature in 2007, when a House committee deadlocked on the proposal.
The amendment has not received a hearing in the House since.
Democratic Sen. Tim Lanane says supporters have made a bad amendment worse by proposing to ban not only marriage but civil unions, a possibility left open in earlier versions. He charges the amendment would lock discrimination into the constitution.
Supporters of the amendment said giving Indiana voters the opportunity to add it to the constitution will protect the state’s marriage law from the whims of court and legislative decisions.
Opponents said it amounts to discrimination and is unnecessary because the state already has a ban on gay marriage.