Top GOP presidential hopefuls are seeking to build their party by latching onto issues that could attract centrist or young voters. The effort is intended to expand the Republican tent and help win a general election, but it could cause a backlash from primary voters.

Potential candidates are walking a fine line on a pathway to citizenship for illegal immigrants, belief in human-caused climate change and a right to gay marriage.

Poll numbers show that pluralities of the public at large hold relatively liberal views on these issues. But among Republican supporters, the picture is very different.

A February CBS/New York Times poll found 54 percent of adults support a path to citizenship, 46 percent say humans cause global warming (12 points more than the number who believe it is a wholly natural development) and 56 percent support the legalization of gay marriage.

Those numbers plunged when only Republican responses were considered. Just 36 percent of GOP supporters backed a path to citizenship, 24 percent thought humans cause global warming and 40 percent endorsed legal gay marriage.{mosads}

Some Republican candidates and strategists worry that the party will suffer at the national level if it gets painted as overly rigid or simply old-fashioned. But breaking from party orthodoxy on these divisive issues risks alienating grassroots supporters. 

Republican candidates are widely perceived to have struggled with Hispanic voters in recent years, for example, in part because of their widespread opposition to immigration reform. But advocating for such reform risks incurring allegations that one is supporting amnesty for law-breakers.   

That might be why even relatively centrist potential candidates for 2016 are adopting nuanced positions on the topic.

Sen. Marco Rubio (Fla.) has stuck his neck out the most among potential GOP candidates by voting for a Senate bill that included a path to citizenship.

Former Florida Gov. Jeb Bush previously supported a path to citizenship then reversed his position last year. New Jersey Gov. Chris Christie called for “a common sense path to citizenship” in 2010 but when asked about the issue on ABC’s “This Week” last year, replied, “I don’t get to make those determinations.” 

Sen. Rand Paul (Ky.) clarified last year that he wants to allow illegal immigrants to stay in the United States while they apply for legal status through the existing system.

Republicans in states with early nominating contests say there could be a little room for movement on immigration in 2016, but the issue of “amnesty” is a potent one.

“If there needs to be immigration reform, they’d be more than open to hear the vision,” Bob Vander Plaats, a Christian conservative leader in Iowa, said of GOP voters in his state. But he emphasized the importance of border security and added, “they’re going to see who’s got a conservative, law-abiding, non-amnesty, common-sense vision.”

Craig Robinson, a former political director of the Iowa Republican Party, said Bush and Rubio, the most outspoken figures on immigration, could be in trouble if the issue comes to the fore.

“Immigration for them is something that they would have to watch,” he said. “Those two candidates would struggle greatly if immigration was a white-hot issue during the campaign.”

New Hampshire might be more open to a relatively centrist stance on the immigration issue. Sen. John McCain (Ariz.), a supporter of immigration reform, won the GOP primary there in 2008, and the state has a long history of politically idiosyncratic behavior.  

“I think there’s an audience for comprehensive immigration reform,” said Patrick Hynes, a Republican operative in the state who worked for Mitt Romney in 2012 and McCain in 2008.

Climate change might have less of an audience among Republicans.

Only Christie has clearly taken the stance that humans cause climate change, saying in 2011 that “it’s time to defer to the experts.” But he also withdrew New Jersey from a northeastern cap and trade program.

Bush and Paul have both cast doubt on a definitive explanation. 

“I would question whether there’s been any movement at all,” Hynes said of New Hampshire Republicans’ receptivity to talk of climate change.  “I think there’s been more movement in concerns about energy prices.”

Jim Rubens, a U.S. Senate candidate in New Hampshire, is one Republican contender who does believe humans cause climate change. But he recently told The Huffington Post that position “is the most difficult part of my campaign.”

The most unanimity comes on gay marriage, with all of the potential GOP presidential candidates officially in opposition.

However, some have at least deployed soft rhetoric on gay rights. Bush said loving gay couples “should be held up as examples.” Paul said the party has to “agree to disagree on social issues.” Christie did not appeal a New Jersey court ruling striking down a ban in his state.

Robinson pointed out that gay marriage “has not been an issue” in this year’s Senate primary in Iowa, which could mean it won’t figure prominently in 2016 either.

“Gay marriage has been legal in this state for five years now,” he said.

The views of young people also show how Republicans might need to adapt for the future.

A Pew poll in March found 61 percent of Republicans between 18 and 29 support gay marriage. In a poll commissioned by an environmental group and carried out by one Republican and one Democratic firm, just 3 percent of voters 18-34 said climate change is not happening.

Matt Moore, the chairman of the South Carolina Republican Party, and, at 32, the youngest state chairman in either party, focuses on reaching out to young people in his early primary state.

“Our party platform strongly supports traditional marriage and that won’t change in South Carolina over the next two years, but it’s important that we treat people with respect and offer solutions on a variety of different fronts,” he wrote in an email.

“The Obama administration has massively failed on privacy and spying, and it’s created a potential flood of young, liberty-minded Republicans,” he added. “I’m telling my generation that we can do better than the Democrats.”