A Democratic Virginia Governor has promised to vote against a constitutional amendment that would formally ban gay marriage.

Mr Kaine refused to sign the bill stating it would have negative consequences for all unmarried couples in the state.

The amendment, which will have its final approval in November, was labelled as vague by the politician because it says the Virginia Constitution should not recognise “another union, partnership, or other legal status to which is assigned the rights, benefits, obligations, qualities, or effects of marriage.”

He said the “broad wording of the proposed constitutional amendment” wording could have an adverse impact on unmarried heterosexual couples.

Mr Kaine said it threatens “the constitutional rights of individuals to enter into private contracts, and also the discretion of employers to extend certain benefits, such as health care coverage, to unmarried couples.

“For those reasons, I will vote against the marriage amendment in November, and I urge other Virginians to vote against it as well.”

Virginia State law bans same-sex unions, but supporters of the constitutional amendment want clarification that unions outside the state would not be recognised.

A similar law was passed in Massachusetts last week.