The Indiana House of Representatives approved a proposal Tuesday that would place the state's gay marriage ban in the state constitution, while leaving the door open to eventual approval of civil unions.

The proposed ban, which cleared the chamber on 57-40 vote, now heads to the Indiana Senate, where members of the Senate Judiciary Committee are set to take up the issue.

The vote followed weeks of uncertainty for a measure that swept through the General Assembly with ease just three years ago.

Republican House Speaker Brian Bosma worked hard to shepherd the ban through the start of the session. But he washed his hands of the measure Monday night, shortly after members of his own caucus joined with House Democrats to change it.

House lawmakers removed a sentence in the proposed ban that would have banned civil unions and potentially barred employers from providing benefits to same-sex employees. Republicans who joined with House Democrats to alter the measure expressed concerns that the ban went too far by barring future approval of civil unions.

However, that alteration potentially pushes back the soonest the measure could go before voters to November 2016. Indiana's constitutional amendment process requires the same measure be approved in two consecutive two-year sessions of the General Assembly then be placed on the ballot for consideration by voters.

But legislative attorneys counselled Republican leaders that altering the language of the ban would likely require lawmakers to give it a second approval when they convene their next two-year session.

The question could easily become moot, however, depending on what the Senate does. Senators have the ability to amend the measure back to its original form. If senators restore the measure to its original form, they could set the ban back on track for an appearance on November's ballot.