As a boatload of candidates eye the White House for 2016, one issue the hopefuls won't be able to escape is immigration policy.

The issue will be one of the key talking points on the campaign trail, and provides a clear demarcation between the two established parties, said Marc Rosenblum, deputy director of the U.S. immigration policy program at the Migration Policy Institute.

"Democrats are eager to pay attention to the issue because they think it helps them with Hispanic and Asian voters," Rosenblum said. "Some Republicans are eager to pay attention to the issue because they think it helps them with GOP base voters."

While the most extreme candidates on either side of the issue may take hardline stances, Rosenblum argued that many independent voters -- and many Americans in general -- favor creating some kind of path to grant legal status to immigrants already in the country.

"It depends on how the question is asked," he said. "But on the core issue -- should most unauthorized immigrants have an opportunity to legalize their status or should they be deported -- I think most independents and most Americans favor some form of earned legalization being on the table."

The numbers back that up. A 2013 Gallup poll showed that "seven in 10 Americans would vote for a law that lets immigrants living in the U.S. illegally have a chance to become 'permanent legal residents.'"

"A more moderate candidate for both parties is what's needed to win, but as we've seen during the last 20 years, the median voter has become more accepting of immigration and legalization than they were during the Clinton administration," Nowrasteh said.

Of the current crop of hopefuls, Nowrasteh highlighted Sen. Marco Rubio as the candidate with the most extensive track record on the matter, pointing to the time he spent authoring a 2013 immigration reform bill in the Senate. Nowrasteh also pointed out Jeb Bush's family history on the matter, emphasizing that George H.W. Bush signed into law the Immigration Act of 1990, while George W. Bush pushed for an immigration bill but failed.

"This is an issue Jeb is particularly keen to work on," Nowrasteh said. "Hilary Clinton has not taken many pro-immigration votes when she was senator, and Sen. Bernie Sanders has a mixed record. He is in favor of legalizing those immigrants here, but against expanding immigration going forward."

The analyst also emphasized the importance of judging candidates based on their voting records rather than the speeches they make.

"In terms of rhetoric, I don't take a lot of that very seriously at this stage," Nowrasteh said.

As candidates move forward, rhetoric won't be enough -- they'll have to answer a few questions about how to make immigration reform a practical reality.

"That includes who is eligible to legalize, what steps they have to go through, and what it means to legalize your status," Rosenblum said. "Does that put you on a path to get permanent residency and a green card, or does it look more like protection from deportation without a green card and opportunity to become a U.S. citizen?"

The answers to those questions will make all the difference to millions living in the country. Pew data published in July shows a population of 11.3 million unauthorized immigrants currently in the U.S. However, finding the right candidate to generate those answers won't be easy.

"That's really the $64,000 question," Nowrasteh said. "It's very difficult to figure out who will be able to do that."

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