INDIANAPOLIS -- The Indiana Senate has approved a proposed amendment to the state constitution banning gay marriage and civil unions.

The 40-10 vote on Tuesday happened below an empty public gallery, which was closed after protesters disrupted the Senate's debate of the resolution Monday.

Current state law prohibits gay marriages. Democratic Sen. Tim Lanane, of Anderson, argued that attitudes toward same-sex marriages are rapidly changing and the amendment would make it difficult for future changes.

"Just go onto the college campuses of our great state. Talk to kids there. You know what they're going to tell you? They don't care about who marries whom," he said.

But amendment sponsor Sen. Dennis Kruse, of Auburn, said the measure would provide maximum protection for the basic family unit of society.

"There are 30 states that now have a marriage amendment to their constitution, and they all passed in all 30 states by an average of 68 percent of the electorate," Kruse said.

The Republican-led House approved the amendment last month. The measure must pass both the House and Senate again in 2013 or 2014 to go before voters on the 2014 ballot.

The Senate Judiciary Committee last week advanced the amendment along party lines.

Earlier this month, executives from Eli Lilly and Co. and Cummins Inc. argued that a ban would hurt their ability to attract talent to the state.

Several hundred people rallied at the Statehouse earlier this month in opposition to the amendment.

In 2005, the Republican-controlled General Assembly passed a similar amendment, but when Democrats won control of the house in 2006, the proposal didn't clear that chamber a second time.