On the issues

Foreign policy: Christie said in April that U.S. combat troops might be needed to fight the Islamic State in Iraq and the Levant. "We have to be willing as Americans to say, if need be, we'll also put soldiers into the fight." He said he had "grave concerns" about a potential deal with Iran to curb its nuclear program, saying that an agreement would lead other Middle East nations to develop nuclear abilities, and that Tehran, as a state sponsor of terrorism, has "no basis to have earned our trust." He criticized President Obama's warming of ties with Cuba, and of Americans who travel there, saying Cubans "can't vote, they can't speak, they can't own property." Addressing Russia's support of separatist rebels in Ukraine, he said that Russian President Vladimir Putin would be more fearful of him than of Obama: "I don't believe, given who I am, that he would make the same judgment."

Environment: "I think global warming is real," he said in April. "And I do think human activity contributes to it." But he withdrew New Jersey from a regional cap-and-trade program intended to limit carbon emissions that cause global warming, and he argued last year against unilaterally curbing emissions when people in China are "doing things to the environment that would never be done in our country."

Immigration: Christie downplays the need for stricter border security. "Walls can be gotten over," he said. "The reason people come here is to work." He says illegal immigration will drop "if we clamp down on folks who are hiring people in this manner." He had New Jersey join a lawsuit against Obama's order seeking to shield millions of undocumented immigrants from deportation, but he says Republicans should work with the president to push such legislation. In 2014, he signed a law letting people in the country illegally pay in-state college tuition rates if they lived in New Jersey for three years and graduated from a high school in the state.

Same-sex marriage: Christie opposes same-sex marriage and vetoed a bill in 2012 that would have allowed it in New Jersey. But the next year he dropped a state challenge to a court ruling allowing same-sex marriage, calling it futile.

Education: Christie said in 2013 that he would be "leading the charge" for Common Core, the national education standards meant to raise proficiency in math and English. But in May he called for new standards for New Jersey, saying Common Core is "simply not working." That has led to charges of flip-flopping, since Common Core standards have drawn fierce criticism from many conservatives who see them exemplifying overreach by the federal government.

Budget and economy: Christie gained wide attention for his confrontation with public employees over benefits and pensions, and he boasted at the 2012 Republican National Convention that he had "fixed" the state's problem of ballooning pension costs. But two years later, he said that New Jersey lacked the money to meet its pension obligations. He has also boasted of balancing budgets and curtailing spending, but the state Constitution mandates a balanced budget, while spending and borrowing have continued to rise. In May he proposed simplifying the federal income tax code from six brackets to three, reducing the top rate to 28 percent from 39 percent, and cutting the corporate tax rate to 25 percent from 35 percent. He would also eliminate the wage tax for anyone older than 62 or younger than 21.

New York Times