ATLANTA (AP) — Retired neurosurgeon Ben Carson has joined the race for the Republican presidential nomination. Here's a look at where Carson, who has never held public office, stands on issues that could help determine the GOP nominee:

IMMIGRATION

Carson argues that several administrations have failed to secure the U.S.-Mexico border "because they do not want to alienate a large voting bloc of Latinos." But he's also called for an expanded guest worker program, saying it would allow people from other nations to "come and go as they please" while paying taxes and building the U.S. economy. In his 2012 book "America the Beautiful," Carson wrote, "Is it moral for us, for example, to take advantage of cheap labor from illegal immigrants while denying them citizenship?" He said the U.S. continues to "to harass and deport many individuals who are simply seeking a better life for themselves and their families."

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FOREIGN POLICY

Carson focuses more on domestic policy but has joined fellow Republicans in excoriating President Barack Obama's handling of the Middle East. Carson called the framework for an Iran nuclear deal "a slap in the face," focusing criticism not on the details but on Obama's initial course of leaving Congress aside in the process. In earlier writings, Carson castigated the political left for its distrust of the military since the Vietnam era. But he's also asserted that the United States, along with the rest of the world, has been too engaged in warfare. In "America the Beautiful," Carson complains that the U.S. has no "consistent policy that governs military intervention." But the closest he comes to spelling out his preferred policy is to ask: "Is any war moral?"

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BUDGETS AND ENTITLEMENTS

Carson blasts the modern welfare state, a "bloated" federal bureaucracy, a national debt he calls immoral, and a complicated tax system he describes as rigged for powerful interests that hire the best lobbyists, lawyers and accountants. He has compared Obama's health care law to slavery. Carson calls existing progressive income tax rates "redistributionism" designed to get votes; he instead endorses a flat income tax, which he justifies citing the Biblical standard of tithing. Invoking a standard Republican argument, he says that tax policy, combined with "relatively painless budget cutting," could spur enough economic growth to yield a balanced budget. Yet even as he warns of creeping socialism, Carson says he's "not one of those persons who thinks that no regulations are necessary." Carson generally has endorsed Medicare as a necessary program but says private charity, supported by capitalism, is preferable to the public safety net.

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SOCIAL ISSUES

Carson attributes his opposition to same-sex marriage and abortion rights to his interpretation of Judeo-Christian scriptures. "One can choose God's word or the gay marriage agenda," he wrote in 2014. He ran into trouble earlier this year when he said homosexuality is "absolutely" a choice; he later apologized. Carson also calls himself a "creationist" and lashes out at evolutionary biologists who criticize his stance. Carson agrees with recent Supreme Court rulings backing the Second Amendment right to own firearms, but said he understands why certain locales, particularly cities, might seek some gun restrictions.

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CLIMATE CHANGE

Carson declines to endorse the body of research demonstrating a rise in global temperatures and sea levels driven by carbon emissions. Carson says people have a responsibility to care for the Earth but federal regulators should work with industry to develop energy resources in a "responsible" way.

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