Obama won both states in November, but Republicans control the state government. Spokesmen for Florida Attorney General Pam Bondi and Ohio Attorney General Mike DeWine, both Republicans, declined comment.
In the seven other states, a Democrat is attorney general. Mississippi Attorney General Jim Hood wants the court to issue narrow rulings in both cases, spokeswoman Jan Schaefer said. "The outcome of the two cases should not directly impact Mississippi law," Schaefer said.
The participants in the two cases and other interested parties have submitted nearly 200 briefs that range from broad historical overviews to personal stories to technical legal matters.
The Catholic Church, the Southern Baptist Convention, the Mormon church and Orthodox Jewish congregations are among the religious organizations urging the court to uphold the California provision.
Supporters of same-sex marriage include Episcopal bishops in California, the United Church of Christ, and the Reform and Conservative movements in Judaism.
There are testimonials in support of gay marriage from the straight parents and siblings of gays and lesbians, as well as from people who call themselves survivors of efforts to help them change their sexual orientation. On the other side, some members of the ex-gay community defend traditional marriage laws, and some gay and bisexual men say the courts should not be involved in defining marriage.
One group of international scholars and jurists argues that reserving marriage for straight couples, while offering other protections for gay Americans, is consistent with practices in other countries. Experts in foreign law claim that upholding Proposition 8 would diminish the U.S. on the world stage at a time when many other nations also are moving toward marriage equality.
The court is expected to rule in the cases by the end of June.