New Jersey Gov. Chris Christie backed away from a court fight over same-sex marriage Monday, a move that further staked his place near the political middle ground at a time the country seems irretrievably divided into warring camps of right and left.

The Republican governor's decision not to appeal a state Supreme Court judgment represents a gamble for his expected presidential effort: that in 2016 — after successive losing campaigns and a politically disastrous government shutdown — a majority of Republican primary voters will be willing to forsake ideological purity for a more pragmatic (and, some suggest, winning) approach.

A Christie bid for president, which is widely anticipated after his likely reelection next month, would test that proposition; victory would represent a sea change for Republicans, who for years have counted heavily on the enthusiastic support of social conservatives, motivated by opposition to abortion and gay rights.

"It would indicate that we're readjusting our focus" and moving "the dialogue away from the narrow ground it's occupied," said Tom Rath, a longtime Republican strategist in New Hampshire, the first presidential primary state.

Hours after New Jersey began holding its first same-sex weddings early Monday, Christie announced he was abandoning his legal fight to keep gay and lesbian couples from marrying. New Jersey became the 14th state in the country to legalize same-sex marriage after a unanimous New Jersey Supreme Court ruling that same-sex couples were being deprived of "the full rights and benefits the state constitution guarantees."

In its decision last week, the court strongly indicated that Christie would lose an appeal, a fact noted in a statement released by the governor's office Monday.

"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," the statement said. "The governor will do his constitutional duty and ensure his administration enforces the law as dictated by the New Jersey Supreme Court."

Though no one would mistake Christie for a Democrat — he is a staunch fiscal conservative, a critic of President Obama's healthcare law and a fierce opponent of public employee unions — his reversal was the second recently in which he edged away from his party's conservative base.

Last week, in a speech to a Latino group, Christie said he supported a bill that would make it possible for students in the state illegally to receive in-state tuition at New Jersey's public universities.

As a Republican governor in a Democratic-leaning state, Christie has compiled a relatively moderate record, which has served him well politically; he is an overwhelming favorite to win reelection next month against his overmatched opponent, state Sen. Barbara Buono.

The victory — especially if it's a landslide — would probably boost a Christie presidential bid, showing his capacity to appeal beyond Republicans to independent voters and Democrats willing to cross party lines. Those are precisely the voters the GOP needs to win back the White House in 2016.

The challenge for Christie will be running on his record in presidential primary contests decided by far more conservative voters.

"Everything he does makes perfect sense in New Jersey," said Craig Robinson, editor of TheIowaRepublican.com, a conservative blog in the state that has traditionally cast the first votes of the nominating process, in its precinct-level caucuses. "His problem is that what's good for him in New Jersey isn't necessarily going to help him in Iowa."

Christie's stand on social issues could prove particularly nettlesome.

The governor has repeatedly stated his personal opposition to same-sex marriage and last year vetoed a bill passed by the Democratic-run Legislature granting gay couples the right to legally marry. But Christie has shunned the harsh rhetoric used by some opponents. He appointed an openly gay judge to the state Supreme Court and signed a law banning so-called conversion therapy aimed at changing the sexual orientation of gay minors, making New Jersey the second state after California to ban the practice.

Although opposed to legal abortion, Christie has not championed the cause. He has also been a supporter of New Jersey's relatively restrictive gun laws.

Moreover, Christie irked fellow Republicans when he warmly embraced Obama in the days before the 2012 presidential campaign, after Superstorm Sandy devastated the New Jersey shore, and when he lashed out at this month's GOP-led shutdown of the federal government.

All of that has made Christie highly suspect to a number of conservative activists. Bob Vander Plaats, head of the Family Leader, a conservative Christian group influential in Iowa politics, was among those issuing statements Monday condemning the governor's move.

"With his recent and enthusiastic embrace of Obama's leadership during the peak of the 2012 election, he already raised some red flags for principled Republicans," Vander Plaats said. "Now, with this decision, he just added more cause for pause."

The countervailing force is a movement within the GOP to back away from social issues like same-sex marriage, which, polls show, has gained increased acceptance in places far afield from the blue bastions of California and New York. A group of major Republican donors, including hedge fund executive Paul Singer, is quietly working to push the party toward a more centrist position.

"Voters in South Carolina are less affected by gay marriage in New Jersey than a government shutdown, sequester, tax increases and Obamacare," said Adam Temple, a Republican strategist based in Charleston, who suggested that 2016 may be the right time for a candidate like Christie.

One thing seems certain: He won't have a lot of competition crowding the middle.

mark.barabak@latimes.com

Times staff writers Chris Megerian and Alana Semuels contributed to this report.