(CNN) - One of the Republicans hoping to succeed California Gov. Arnold Schwarzenegger next year is claiming that the governor violated the state constitution by signing a bill recognizing out-of-state same-sex marriages.
Former Rep. Tom Campbell supports same-sex marriage and disagreed with the successful ballot initiative, Proposition 8, that put in place a constitutional ban on such marriages in the state.
But he opposes elements of the bill Schwarzenegger signed on Sunday, SB 54, which recognizes same-sex marriages performed in states other than California before November 5, 2008, when voters approved Proposition 8.
In an e-mail to CNN, Campbell wrote that the ban on same-sex marriage can only be modified by amending the constitution, as Californians voted to do last year. Schwarzenegger's action, he argued, "constitutes an unconstitutional attempt to do this by legislation."
Schwarzenegger also said the bill grants legal rights and protections to same-sex couples who married out of state after November 5. He wrote in a signing statement that while the state will not recognize such couples as 'married,' it will "provide the same legal protections that would otherwise be available to couples that enter into civil unions or domestic partnerships out-of-state." Civil unions remain legal in California.
Campbell claimed that provision offers same-sex couples married out-of-state after November 5 advantages over California couples who obtain civil unions in the state.
"In other words, SB 54 creates two categories of gay couples: those who were married out of state after Proposition 8 became law, and those who entered civil unions in California after Proposition 8 became law - and it accords greater rights to the first group," he wrote. He said that difference in treatment is also unconstitutional.
Campbell's two rivals for the GOP gubernatorial nomination, State Insurance Commissioner Steve Poizner and former eBay CEO Meg Whitman, had different reactions to the bill.
Poizner is flatly opposed to same-sex marriage. "Therefore, he would be against recognizing same-sex marriages from other states in California," said Poizner spokesman Jarrod Agen.
A spokesman for Whitman, Tucker Bounds, didn't have a comment on Schwarzenegger's action, except to note that the candidate might talk about the issue "to the extent it's discussed along the campaign trail."