"This amendment permanently threatens liberty for all Hoosiers and sends the message that our state is an unwelcoming place that values neither freedom, nor fairness," said Chris Paulsen, president of Indiana Equality Action, a leading gay rights group.
At a Freedom Indiana kick-off rally Wednesday, Paulsen was joined by Rob Smith, an executive at Eli Lilly and Co., and representatives from Cummins Inc., Freedom to Marry, Gill Action, American Unity Fund, American Civil Liberties Union and the Human Rights Campaign.
They announced plans to build and support grassroots organizations in communities across the state urging lawmakers to vote against the pending amendment and then taking the fight to Hoosier voters if the amendment is approved by the General Assembly for ratification.
"It doesn't matter whether you're straight or gay; male or female; young or old; rural or urban; Republican, Democrat or Libertarian, this is a bipartisan initiative that requires all of us to work together to protect our Indiana Constitution," said Megan Robertson, a Portage native and manager of the Freedom Indiana campaign.
Robertson is a Republican that has helped elect Hoosiers to Congress, ran the successful 2011 re-election bid of Indianapolis Mayor Greg Ballard and worked on two GOP presidential campaigns.
She said the amendment threatens the core economic development issues Hoosier Republicans support.
"Indiana has always been a welcoming community known for our Hoosier hospitality," Robertson said. "This amendment directly contradicts the reputation that has helped us recruit jobs and economic investment for our state."
Smith said Eli Lilly, the Indianapolis drug giant, believes if the constitution is changed the company will be unable to recruit the talent they need to develop drugs that improve lives.
"Our values and our commitment to diversity require us to take a stand in opposing this amendment," Smith said.
To date, a similar organization of groups supporting the amendment has not been formed. Gov. Mike Pence, House Speaker Brian Bosma and Senate President David Long, all Republicans, have endorsed the proposal.
Indiana law already limits marriage to opposite sex couples. The amendment, which was previously approved by the Republican-controlled General Assembly in 2011, would make that law extremely challenging to change and takes the additional step of prohibiting civil unions.
If majority of lawmakers in both the House and Senate approve it again next year, the amendment will be on the Nov. 4, 2014, ballot when Hoosier voters would have the final say.