ASBURY PARK — Wealthy activists and gay-rights advocates from across the country joined the battle to legalize same-sex marriage in New Jersey today, along with a Republican billionaire who encouraged Gov. Chris Christie to run for president last year.

The same-sex marriage campaign also gained a new name, "New Jersey United for Marriage," as its leaders vowed to lobby state legislators, business groups, major corporations and religious leaders — and to knock on doors, hit the phones and possibly buy television ads to ensure that gay marriage will be legalized by the end of the year.

After the U.S. Supreme Court struck down the Defense of Marriage Act last month, Garden State Equality and the American Civil Liberties Union of New Jersey launched a new push to allow gay marriage in the state.

At a boardwalk rally in Asbury Park, more than 100 gay-rights supporters welcomed five more groups — the Human Rights Campaign, the American Unity Fund, the Gill Action Fund, Freedom to Marry and Lambda Legal.

"For nine long years, Garden State Equality and our 130,000 members have marched a marathon towards equality, and we’ve reached the final stretch," said Troy Stevenson, the Garden State Equality executive director. "All up and down the Northeastern seaboard of this country right now — from Ogunquit, Maine, to Rehoboth Beach, Delaware — gay couples are getting married in beaches just like this, but not in New Jersey and not in Asbury Park."

The Supreme Court decision extended more than 1,000 rights and benefits to same-sex couples — but they are allowed to marry only in 13 states and the District of Columbia. New Jersey allows civil unions for gay couples.

Gov. Chris Christie last year vetoed a Democratic bill to legalize gay marriage, and he blasted the Supreme Court for overturning DOMA.

"If you want to change the core of a 2,000-year-old institution, the way to do that is to put it in front of the voters in the state of New Jersey and let them vote," Christie said this month, calling for a ballot question to settle the issue.

Stevenson and Democratic lawmakers who control the Legislature have ruled out pursuing a voter referendum. Instead, they have promised to hold a vote to override the governor’s veto before the end of the year. An override requires a two-thirds majority in each chamber, and Democrats say they need a handful of Republicans to switch their "no" votes to "yes."

Udi Ofer, executive director of ACLU-NJ, said Christie is out of step with his home region in the Northeast and with powerful voices in his own Republican Party. The American Unity Fund was started by Paul Singer, a major GOP donor and hedge-fund billionaire who supports Christie and encouraged him to seek the presidency last year. "There are prominent voices within the Republican Party that support marriage equality, and not only prominent voices but wealthy voices," Ofer said

At today’s rally, Penny Gnesin and Sue Fulton of North Plainfield said they registered first as domestic partners, entered a civil union in 2007 when the state allowed those, and had hoped to marry someday in New Jersey.

But after Christie vetoed the bill last year, they instead became the first LGBT couple to wed in the West Point Cadet Chapel in New York, where same-sex marriages are legal. Fulton was in the first female class to graduate from the military school in 1980.

"I graduated from Long Branch High School, I went to Rutgers University and I worked for AT&T," Gnesin said. "I’m a Jersey girl through and through. … Why do I not have equal rights, the equal marriage rights that my parents had?"

New Jersey will also be a battleground state for gay marriage opponents, said Brian Brown, executive director of the National Organization for Marriage. He said several Republicans who have changed their minds were challenged in primaries and lost their seats.

Garden State Equality and Lambda Legal are arguing in state court that New Jersey must legalize same-sex marriage immediately because the DOMA ruling turned civil unions into second-class unions with unequal rights. A hearing is scheduled Aug. 15 in Superior Court.

The Associated Press contributed to this report.

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