SAN FRANCISCO – Presidential candidate Barack Obama has come out against a ballot measure that seeks to outlaw same-sex marriage.

A club for gay Democrats in San Francisco says it solicited a statement from the Illinois senator's campaign in which he called the proposed constitutional amendment “divisive and discriminatory.”

Obama also extended congratulations to gay and lesbian newlyweds who have gotten married in California over the last two weeks.

His letter was read aloud at the Alice B. Toklas LGBT Democratic Club's annual gay pride breakfast on Sunday.

Last week, Republican rival, Sen. John McCain, endorsed the gay marriage ban that is slated to appear on the November ballot.

Obama has said he is personally opposed to same-sex marriage but thinks the issue should be left to states to decide,