Cheney, who lives in Virginia with her wife Heather Poe, has become more vocal on the issue since her public spat with sister after Liz Cheney spoke out against gay marriage last month during her campaign for a Wyoming Senate seat.
Mary Cheney spoke out against HJR6, a bill being considered in the Indiana legislature that would only recognize heterosexual marriages as valid and says that "legal status identical or substantially similar to that of marriage for unmarried individuals shall not be valid or recognized."
Gay marriage is already outlawed in Indiana, but critics fear HJR6 would go beyond that and limit benefits for same sex couples.
"This is an incredibly personal issue for me, one that couldn't possibly hit closer to home," Cheney told supporters of Freedom Indian on Wednesday. The video of her remarks was posted today.
Concerns with the legislation center around its vague language and uncertain implications for same-sex couples if it were to be passed. Freedom Indiana states on its website that in addition to their opposition to the elimination of same sex marriage validity in Indiana, that "no one has been able to clearly define what effects the second sentence would have on existing marriages, domestic partner benefits, human rights ordinances, legal contracts and benefits for unmarried couples."
Cheney highlighted her conservative bona fides in the speech.
"I'm pro-life. I'm pro gun. I think more government is almost never the solution to any problem, and I believe you can't have personal freedom without personal responsibility," Cheney said emphatically. "And as a conservative I also believe that strong families are the cornerstone of our society…families regardless of how they look or how they're made or where they live…deserve to be treated with the same respect, dignity, legal rights and recognitions as every other."
"This isn't about marriage equality. This is about standing up and opposing an amendment that would hurt Indiana's economy, impact the state's future development, and potentially devastate many of the state's families," said Cheney. "But while we may never agree on marriage equality, we can certainly all agree that this amendment is not the way to deal with the issue."
Dick Cheney recently weighed into the controversy between his two daughters. "We were surprised that there was an attack launched against Liz on Facebook, and wished it hadn't happened," Cheney said at the National Press Club last week. "It's always been dealt with within the context of the family and frankly that's our preference.
Mary Cheney and Heather Poe were legally married in front of a judge in Washington, D.C. a little over a year ago. The couple of over 21 years have a son and a daughter.