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."