In public speeches and private appearances, Corzine, who as recently as 2006 said he believed marriage should be between a man and a woman, has touted his support of same-sex marriage.

In raising the issue, he has tried to draw a bright-line divide with his Republican opponent, Christopher J. Christie, who has said he would veto a bill allowing gay and lesbian couples to wed.

"We believe that government should allow people the freedom to marry whomever they love," Corzine said in his general-election kickoff speech June 2.

At a gay-pride parade days later in Asbury Park, N.J., Corzine referred to his campaign and told cheering revelers: "Marriage equality is on the ballot. Are you going to help us make it come to pass in New Jersey?"

His campaign posted a video clip online showing the event.

Corzine has focused on blue-state values early in the race, stressing differences between Democrats and Republicans on abortion, gun control, and the environment. That his kickoff speech gave same-sex marriage a prominent place alongside these other issues heartened gay-rights groups.

Steven Goldstein, chairman of Garden State Equality, said the campaign reflected Corzine's "evolving" views and the swiftly shifting politics of the issue.

"New Jersey is undergoing a sea change in how politicians are looking at marriage equality," Goldstein said. "It doesn't take a rocket scientist to figure out that when a candidate campaigns on an issue, it's not only because he or she believes in the issue, but also because the candidate believes it's a political plus."

Goldstein said momentum had grown recently, especially in the Northeast, after gay marriage became legal in New Hampshire, Maine, Vermont, Connecticut, and Iowa. They joined Massachusetts as the only states allowing such unions.

In New Jersey, lawmakers are talking about approving same-sex marriage in the lame-duck session after this year's election but before new officials take office.

Corzine has not always backed the idea.

While running for governor in 2005, he said he held that "the fundamental and traditional view of marriage is between a man and a woman."

He has long said he would sign a same-sex-marriage bill if lawmakers approved it, but did not publicly push the idea until recently.

When the state Supreme Court in 2006 ordered New Jersey to provide equal rights to gay and lesbian couples, Corzine endorsed civil unions as his "preference" for meeting that goal.

In December 2006, he signed the civil-unions bill, calling it a proud moment.

But on same-sex marriage, he said, "That is not where my personal views are because I was brought up in the context of religious beliefs that would define marriage as between a man and a woman," according to a report in the Star-Ledger of Newark.

In December 2008, however, Corzine took a public step toward embracing marriage for gays and lesbians after a state commission, with Goldstein as its vice chair, issued a report saying civil unions failed to provide equal rights. Corzine called the disparity a civil-rights issue that "must be addressed sooner rather than later."

At a Garden State Equality event in February, Corzine went further.

"I'm straight, and I believe in marriage equality," he said.