The veto came a day after the state Assembly passed the bill. The state Senate had passed it on Monday. Christie, a Republican who opposes same-sex marriage, had vowed "very swift action" once the measure reached his desk.

In returning the bill to the Legislature, Christie reaffirmed his view that voters should decide whether to change the definition of marriage in New Jersey. His veto also proposed creating an ombudsman to oversee compliance with the state's civil union law, which same-sex couples have said is flawed and promotes discrimination.

In Maryland, the state appeared ready to legalize gay marriage after the bill to allow it passed a long-standing hurdle in the Maryland House of Delegates on Friday.

After courting the votes of a couple delegates initially opposed to the measure, House members voted 72-67 to pass the bill. An initial vote count suggested the measure passed with 71 votes, leaving out an affirmative from Delegate John Bohanan.

Next up is the Senate, which handily passed a similar bill last year. Gov. Martin O'Malley sponsored the bill and has pushed for gay marriage to be legalized. Approval would make Maryland the eighth state to legalize the marriages, although opponents have vowed to petition the measure to referendum.

Proponents of the New Jersey bill said gay marriage is a civil right being denied to gay couples, while opponents said the definition of marriage as a heterosexual institution should not be expanded. The legislation contains a religious opt-out clause, meaning no church clergy would be required to perform gay marriages and places of worship would not have to allow same-sex weddings at their facilities.

Another gay marriage supporter, Washington state Democratic Gov. Chris Gregoire, also reached out to Christie, a practicing Catholic. Gregoire sent the governor a letter last month offering to talk about gay marriage because, in her words, "while I am a Governor, I am also a Catholic."

The Roman Catholic Church opposes same-sex marriage.

Gregoire signed a gay marriage measure into law in Washington on Monday. Her spokeswoman, Karina Shagren, said Christie hasn't responded to the letter.

Thirty states, including South Carolina, have adopted constitutional amendments banning same-sex marriages, most by defining marriage as a union between a man and a woman.

Six states and Washington, the capital district, allow gay marriage. Washington state's new gay marriage law is set to go into effect in June.

Lawmakers in New Jersey have until the end of the legislative session in January 2014 to override the veto.

Democrats are hoping that support for gay marriage - 52 percent for gay marriage, 42 against it, in New Jersey, according to one recent voter poll - will continue growing.