A second high-profile Republican in the US state of Ohio, the former attorney general, has come out in support of equal marriage.

Jim Petro, the state’s former attorney general, made the revelation at a press conference on Monday, as he appeared at a rally organised by pro-equality group FreedomOhio.

The organisation is spearheading the effort in the state to legalise equal marriage by overturning its ban on same-sex marriage.

Equal marriage advocacy group FreedomOhio hopes to put a constitutional amendment on the ballot for Ohio later this year or next, which would remove the 2004 amendment which banned equal marriage.

In 2004, the amendment banning equal marriage passed with 62% of voters supporting.

Greg Schulz, a key player in Obama’s reelection campaign, recently joined the executive committee of FreedomOhio.

Petro was the second Ohio Republican to announce his support, as Senator Rob Portman who was among the original sponsors of the Defense of Marriage Act (DOMA) became the first to announce that he had changed his anti-equal marriage stance. It followed the personal revelation of his own son’s coming out as gay.

The pair’s support for same-sex marriage could prove to be influential as FreedomOhio intends to put the issue before votes in the 2014 general election. To get on the ballot the organisation must find 385,245 signatures.

Following shortly after Portman’s announcement was GOP Senator Mark Kirk, who also came out in support.

Writing in an op-ed shortly after Kirk’s revelation was, Republican Senator Lisa Murkowski of Alaska, who announced her support for measures towards marriage equality, and became the third Republican Senator to do so.