President Bush will promote a constitutional amendment banning gay marriage, a cause dear to his conservative backers, at a Rose Garden event Monday, the eve of a scheduled Senate vote on the issue. The amendment would prohibit states from recognizing same-sex marriages. To become law, the proposal would need two-thirds support in the Senate and House, and then be ratified by at least 38 state legislatures. It stands little chance of passing the 100-member Senate, where proponents are struggling to get even 50 votes. Several Republicans oppose the measure, and so far only one Democrat — Sen. Ben Nelson (news,...