Kentucky’s chief lawyer Jack Conway went against his governor and arguably the will of his constituents when he tearfully announced on Tuesday he wouldn’t defend a Kentucky law banning recognition of out-of-state gay marriages.

“I felt like I would be defending discrimination,” the Democratic attorney general told TPM in an interview on Tuesday. “And for me that’s a line in the sand. I couldn’t do it.”

It was a rare and extraordinary move that split the administration of Gov. Steve Beshear (D), who revealed that he would appeal a federal judge’s ruling against the statute after his top lawyer refused to do so.

“I’ve known for the last couple of days that’s where he was headed. I respect Steve Beshear. I had a duty to defend the law … and I read the [judge’s] decision, I agreed with it, and I informed my client I agreed with it,” Conway said, citing attorney-client privilege in refusing to divulge the details of their conversations.

Conway, who opposed same-sex marriage during his failed run for the U.S. Senate in 2010, wouldn’t pinpoint when he changed his mind to support full marriage equality. He said he came around “over the last few years” after conversations with friends in the gay community, and after thinking about how his two daughters would come to view his decision.

“I thought long and hard. I thought about the arc of history,” he said. “I thought about the fact that at one time in this country we discriminated against women. At one time we discriminated against African-Americans and people of color. At one time we discriminated against those with disabilities. This is the last minority group in this country that a significant portion of our population thinks it’s OK to still discriminate against in any way. And I didn’t think that was right.”

His conversion coincides with that of millions of Americans, who in recent years have shifted rapidly toward support for gay marriage. Marriage equality polls at over 50 percent nationally, but notably, not in the Bluegrass State: 55 percent of Kentucky voters oppose gay marriage, while 35 percent support it, according to a poll last month. The Supreme Court struck down that prohibits federal recognition of gay marriage, and a flood of lower court decisions suggests the court may soon end up deciding whether gay marriage is a constitutional right.

“To discriminate and not allow two people to marry does not have a rational basis under the law, and therefore it cannot withstand scrutiny under the equal protection [clause of the 14th Amendment],” Conway said, arguing that laws against gay marriage are unconstitutional.

Barring a sudden and swift change in statewide public opinion, the decision poses potential dangers for the attorney general, who has served in the role since 2008, and told TPM he intends to run for governor in 2015 once Beshear maxes out his two terms.

“My wife Elizabeth knew what I wanted to do in my heart,” he said. “And at one point she pulled me aside and said ‘Jack, you stink when you’re not authentic.’ And at that point I knew it might cost me politically but I needed to … make a decision I could be proud of.”

Conway shed light on his thought process in recent days that led to his move.

“I’d made my decision internally Friday of last week. And over the weekend I wrote the statement myself. And I didn’t anticipate getting emotional at the end,” he said. “But I’ve sort of been in the middle of a maelstrom here for the last little bit — I’ve been under siege from both sides. And I thought about all the people who’d privately written my notes and talked to me. … I got to a point where I realized that if I took it any further I’d be defending discrimination, and that I couldn’t do.”