The second sentence could also potentially ban employer benefits for same-sex couples. Removing that part of measure was a small victory, but opponents will still look to defeat the measure outright, said Jennifer Wagner, spokeswoman for Freedom Indiana.
"It's two tracks," Wagner said. "We'd obviously love to see it defeated. But if that's not a possibility, than the best outcome for us is the second sentence stays out."
House lawmakers approved the altered version of the ban Tuesday afternoon, one day after they had removed the ban on civil unions. If Senators approve the amended House bill, it will likely delay a referendum on the amendment until 2016.
But supporters of the proposed ban could find a way to get the measure back on track for the November election. Republicans control the Senate 37-13, and the proposed ban sailed through the Senate with bipartisan support in 2011.
"Advance America still believes that Hoosiers should have the opportunity to vote on November 4th to protect marriage between one man and one woman. In order to do this, Advance America will be working with Senators to add the language back into HJR 3 that was taken out in the House of Representatives on January 27th so Hoosiers can vote November 4th to protect marriage," wrote Advance America, one of the groups supporting HJR 3, in a message to their supporters urging them to lobby their senators.
One of the potentially most powerful voices on the issue, Republican Gov. Mike Pence, has stood largely by the sidelines during the legislative debate.
Pence included a request in State of the State address that lawmakers settle the marriage question this year, and he rallied hundreds of HJR 3 supporters gathered at an Indianapolis hotel last week.
But Pence's staff said Wednesday he would not answer questions about anything other than the state's propane shortage during a Statehouse news conference, and Pence declined to answer questions about the issue as he left the event.
Senate President Pro Tem David Long, R-Fort Wayne, is scheduled to talk about the measure's prospects in the Senate on Thursday morning.