WASHINGTON (AP) — Immigration, a prominent issue as the presidential campaign begins in earnest, is a complicated, emotional and broad subject. But for political purposes there's a very real question to be answered: What to do about the estimated 11 million people in the country illegally.

With Republicans in Congress unable to agree on an answer, President Barack Obama has taken executive action to limit deportations. All Republicans running for president oppose that step. But they're squeezed between big donors, who largely favor liberalization of immigration policy, and many primary voters, who don't.

A look at where some of the 2016 candidates stand on the issue:

Hillary Rodham Clinton: In a speech Tuesday, Clinton came out fully in favor of a path to eventual citizenship for most people here illegally. The Democratic candidate also pledged to expand Obama's executive actions if Congress does not move on an immigration overhaul. Her position could earn wide support among growing groups of Hispanic and Asian voters and stands apart from the more restrictive views of the Republican contenders.

Jeb Bush: The former Florida governor has endorsed a path to permanent legal status, short of citizenship, for people here illegally, but he has left the door open for the possibility of eventual citizenship. Bush opposes Obama's executive actions. He has also called for an overhaul of the country's legal immigration process to focus more on letting in needed workers rather than letting families reunify.

Perhaps his most striking departure from his Republican rivals is in his tone. Bush, who wrote a book on immigration, says those who have come to the U.S. illegally did so as "an act of love" to make a better life for their families. His wife is Mexican, he's bilingual and he hasn't been shy about speaking Spanish in the campaign.

Marco Rubio: The Florida senator and son of Cuban immigrants once led a push for immigration overhaul and favored eventual citizenship under certain conditions — putting him arguably to the left of Bush on the subject. But he backed off and repositioned.

Rubio co-authored a Senate bill that would have made citizenship possible for people in the U.S. illegally, once they learned English, paid back taxes and passed a background test. The bill passed the Senate but died in the House. Rubio now says a piecemeal approach is required because comprehensive legislation can't succeed. His approach is to start with securing the border and end with letting people who are in the U.S. illegally stay.

Immigrant rights groups say that end would never come, because people would always complain the border was not secure.

Like Bush, Rubio argues for a legal immigration system based more on immigrants' potential economic contributions than on letting them join family members already in the United States. Additionally, Rubio has said he would not immediately overturn one of Obama's actions, which allows people brought here illegally when they were young to stay.

Chris Christie: The New Jersey governor once embraced letting people who are in the country illegally stay, then he became quiet about the subject. Recently, he's hinted at backing some sort of legal status, saying the question of citizenship is a distraction, there's no way to deport 11 million people and most are here to work.

Mike Huckabee: The former Arkansas governor is among the many Republicans who vow to focus on border security. Yet he argues for a path to citizenship for young people who were brought to the U.S. illegally by their parents, and as governor supported a proposal that would have made those children eligible for in-state tuition at public colleges and universities in Arkansas. He says children shouldn't be punished because their parents broke the law. Arkansas did not adopt the plan.

Rand Paul: On one hand, the Kentucky senator has voiced frustration with fellow Republicans who describe any policy as "amnesty" if it would somehow let people here illegally stay. And he's said there is no way to deport everyone. On the other hand, he has not endorsed a specific way to allow people to stay. He voted against the one concrete proposal in Congress to permit that: the immigration bill Rubio co-authored.

Scott Walker: The Wisconsin governor once supported citizenship for people here illegally. He now says he opposes that. He recently told a Republican group in New Hampshire he'd be fine with legal status — essentially adopting Bush's position. But he has also questioned whether the current policy on legal immigration makes economic sense, suggesting he might side with those who believe high numbers of immigrants end up lowering workers' wages.

Ted Cruz: The Texas senator has been seen as the Republican field's firebrand on immigration. In the Senate, he was the most aggressive in pushing to slow down government business unless Obama rescinded his executive actions limiting deportations. He also voted against the Senate immigration bill pushed by Rubio. But even Cruz has declined to rule out eventually letting people in the country illegally stay. He says the border must be secured first, and the visa system changed. Only then, Cruz says, can the country discuss what is to be done about people here illegally.

All three senators in the race — Cruz, Rubio and Paul — voted against legislation to finance the Homeland Security Department in a budget dispute that arose as a protest against Obama's executive actions on immigration.

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Riccardi reported from Denver.