"This issue is too big and too consequential not to trust the people who will be governed ultimately by any change in law or maintenance of the current law," Christie said, suggesting that even the civil-rights battles of the 1960s could have been avoided had the issue been put to a referendum. "So I say today, let the people decide."
Moments later, back in Trenton, Democrats, who have made same-sex marriage their top legislative priority for the year and who control both houses, responded with a resounding "no."
"Civil rights will not be placed on the ballot," said Senate President Stephen Sweeney to applause from a jam-packed hearing room.
Shortly thereafter, the Senate Judiciary Committee voted 8-4 along party lines for the same-sex-marriage bill, which now goes to a vote in the full Senate.
By urging Republican legislators to support his call for a referendum, Christie effectively took away any potential GOP support for the gay-marriage bill, Democrats said.
Several Republicans said Tuesday they favored Christie's proposal, and so Democratic hopes of pulling enough Republican support in the legislature to override a Christie veto of their bill appeared shattered.
Christie alleged that unspecified "elements" in the Democratic Party were trying to make the issue "into a political football," but he specifically said Sweeney was not one of them. "I do not question the sincerity of the Senate president one bit on this," he said.
Sweeney abstained from voting on same-sex marriage when it last came to a legislative vote, in 2010. The measure failed. He now says he did it for political calculations then, and says New Jersey needs to join the six other states and 10 countries that sanction gay marriage.
"The governor is a very decent human being," Sweeney said. "I'm asking the governor to look in his heart. This is about civil rights."
Sweeney was the first to testify at an emotional three-hour hearing Tuesday, where about two-thirds of the witnesses spoke in favor of the bill. Sweeney said "the sky hasn't fallen" in states with marriage equality.
"The issue is not about religion," he said. "It's about civil rights . . . basic civil rights. Nothing more."
The audience - which included dozens of clergy of various Christian and Jewish congregations - was mostly restrained, standing to cheer or jeer only after the vote.
Much of the testimony centered on the alleged failure of civil unions, which have been allowed in New Jersey since 2007. Gay couples described awkward if not unpleasant experiences in emergency rooms - and in one case, at a funeral home - because of public unfamiliarity with the concept of a civil union.
Opponents said they sympathized with the couples but suggested that improved public education about and enforcement of the civil union law would reduce such incidents.
Christie said he favors strengthening the civil union law, and has directed his health commissioner to look into complaints from couples in civil unions who have been denied hospital visitations.
Rutgers-Camden law professor Robert Williams said he was surprised by Christie's announcement because if the governor wanted a simple vote on making gay marriage legal, a referendum seeking approval for it was unprecedented nationally and "legally unnecessary."
A new marriage law rather than a constitutional amendment would suffice, he said. "The legislature already has this authority."
There's also a philosophical question at play in regard to the referendum. Supporters of same-sex marriage say the issue is equivalent to Jim Crow-era laws banning interracial marriage, and such a fundamental legal question should not be left to the whims of the public.
Sally Goldfarb, a Rutgers-Camden law professor who specializes in family law and gender discrimination, said fixing the civil union law is not possible.
"The problem is, when you give it a different name, people routinely think of it as different status," Goldfarb said. "We've been trying for close to five years and people still don't know what civil union is."
The issue, though, is "bigger than just the word" marriage, Christie said, and changing the law affects "everyone" - not just gays.
"It's hundreds of years of tradition . . . legally, societally, and religiously. And that's what I stand up for and am protecting," he said.
At the same time, he said, there's nothing "so special about this particular issue that it must be handled by a legislature."
"The fact of the matter is, I think people would have been happy to have a referendum on civil rights rather than fighting and dying in the streets in the South," he said.
Referendums on issues deemed by supporters to be civil-rights matters have a mixed history.
In 1915, New Jersey put a referendum on the ballot for women's suffrage. It failed, said Ronald Chen, former public advocate under Gov. Jon S. Corzine. At Tuesday's hearing, he presented a letter from 127 law professors from around the country who said the civil union law, which provides some of the rights of marriage, cannot be fixed.
More recently, voters in Maine overturned a state gay-marriage law, while California voters banned same-sex marriage by referendum in 2008. Similar referendums are pending elsewhere.
Washington State is on the verge of approving gay marriage through legislative approval and gubernatorial signature, but opponents then plan to have a question put on the ballot rolling it back.
A similar situation is playing out in Maryland. There, the governor and other backers of a same-sex-marriage bill are trying to head off objections by including in it legal protections for religious groups that decline to conduct such marriage ceremonies. The measure proposed in the New Jersey legislature also contains similar protections.
Monmouth University pollster and political scientist Patrick Murray said Christie's proposal indicates that "politically, he doesn't want his fingerprints anywhere near this."
Although vetoing the bill could help him if he ran in the 2016 presidential GOP primary, Murray said, it would also allow New Jersey Democrats during a 2013 reelection bid "to paint him as someone who kowtows to the socially conservative wing of the party and is not concerned with his constituents here in New Jersey."
So Murray said Democrats will first force Christie to veto their bill. Then, they will look at the political tea leaves to see if a ballot initiative can pass in November.
Even though a recent Quinnipiac University poll showed that 52 percent of New Jerseyans support gay marriage, the California ballot question in 2008 offers a lesson for Democrats.
Gay marriage there was banned, Murray said, in part because it was opposed by socially conservative African Americans who turned out in large numbers to vote for Barack Obama.
Obama is again on the ballot in November, presenting a similar potential pitfall.
Christie on Tuesday said the ballot measure should be posted for this November exactly because it's a presidential year and will bring the most voters out to the polls.
Even after a veto, Democrats still might not ask for a referendum.
Democrats "don't want to put it on the ballot and have it fail because that would probably end the debate over this for quite some time," Murray said. "It really is a very complex calculation that supporters of gay marriage would have to do before deciding to put this on the ballot."
See a video about the debate over gay marriage in Trenton at www.philly.com/gayNJ
Contact staff writer Matt Katz at 609-217-8355, email@example.com, or @mattkatz00 on Twitter. Read his blog, "Christie Chronicles," at philly.com/christiechronicles.
Inquirer staff writer Kevin Riordan contributed to this article, which also contains information from the Associated Press.