President George W. Bush will back a US constitutional amendment banning gay marriage in an attempt to halt same-sex unions like the thousands that have been allowed this month in San Francisco, his spokesman said yesterday.

　　"He has always strongly believed that marriage is a sacred institution between a man and a woman," White House press secretary Scott McClellan said.

　　He said the president wants to end "confusion" that has arisen from court decisions in Massachusetts, and San Francisco's permitting same-sex unions.

　　He said Bush believes that legislation for such an amendment "meets his principles" in protecting the "sanctity of marriage" between men and women.

　　But Bush was not expected in to specifically embrace any particular piece of legislation. White House officials say that support for the proposed amendment has been unraveling in the Senate.

　　Bush decided to take action partly because the Massachusetts Supreme Judicial Court recently ruled that it is unconstitutional to bar gay couples from marriage.

　　(The Associated Press)