Just hours after gay couples began exchanging vows with the blessing of New Jersey's Supreme Court, Christie announced he was withdrawing his appeal to the high court.
New Jersey is the 14th state to legalize gay marriage.
As the Republican governor seeks re-election two weeks from now and ponders a run for president in 2016, Christie's decision holds both risks and benefits for him.
It delighted gay rights activists and could enhance Christie's appeal to independents and moderates of both parties. But it angered members of the GOP's conservative wing, which already distrusts Christie and wields outsized influence in some state primaries.
Bob McAlister, a veteran Republican strategist in South Carolina, said Christie's latest move "is absolutely going to hurt him."
"Abandoning foundational principles that go beyond politics is not the way to get positive attention in South Carolina," he said.
Brian Brown, president of the conservative National Organization for Marriage, said he was "extremely disappointed" with Christie's decision, which he portrayed as "effectively throwing in the towel on marriage."
Last year, the New Jersey Legislature passed a bill to legalize gay marriage, but Christie vetoed it. The issue ended up before Christie again after a trial-level judge ruled last month that the state must allow same-sex couples to wed.
Christie appealed that ruling to the state Supreme Court. The court agreed to take up the case but unanimously refused on Friday to delay the start of gay weddings in the meantime, saying the state had little chance of prevailing in its appeal. Same-sex couples began exchanging vows Monday just after midnight.
Advisers to the governor said that in dropping the appeal, Christie had stayed true to his principles.
"Although the governor strongly disagrees with the court substituting its judgment for the constitutional process of the elected branches or a vote of the people, the court has now spoken clearly as to their view of the New Jersey Constitution and, therefore, same-sex marriage is the law," Christie spokesman Michael Drewniak said in a statement.
"The governor will do his constitutional duty and ensure his administration enforces the law as dictated by the New Jersey Supreme Court."
Although New Jersey is a Democratic-leaning state, polls show Christie holds a commanding lead against Democratic state Sen. Barbara Buono ahead of the Nov. 5 election.
The governor has positioned himself as a straight-talking pragmatist who can win support across the political spectrum.
Even as he has opposed gay marriage, Christie has preached tolerance. He nominated an openly gay judge to the Supreme Court and signed legislation last summer barring therapists from trying to turn gay youngsters straight.
During a debate last week, Christie said if one of his children came out as gay, he would "grab them and hug them and tell them that I love them."
Many conservatives distrusted Christie at least as far back as a year ago, just before Election Day, when he praised President Barack Obama in the aftermath of Superstorm Sandy.
When conservatives gathered in Washington recently for the Family Research Council's annual Value Voters summit, the ballroom heard from such potential presidential candidates as Sens. Marco Rubio of Florida, Ted Cruz of Texas and Rand Paul of Kentucky and former Pennsylvania Sen. Rick Santorum. Christie was not invited.
But many establishment Republicans contend that social issues ultimately will take a back seat to economic ones as gay marriage becomes more widely accepted in America.
"Opposing the freedom to marry is a loser for our party and serves to drive away a growing number of voters who have turned the page," said David Kochel, a top adviser to Republican Mitt Romney in Iowa during the 2008 and 2012 presidential campaigns.
Some Republicans said Christie's decision won't hurt him much if he decides to seek the White House, especially in a crowded primary field populated with several conservatives who could end up splitting the vote.
Conservatives "were never going to be his voters anyway," said John Ullyot, a Republican strategist and former Senate aide.
Thomas reported from Washington. Associated Press writers Angela Delli Santi in Trenton, Thomas Beaumont in Des Moines, Bill Barrow in Atlanta and Charles Babington in Washington contributed to this report.