DES MOINES, Iowa (AP) — A look at where former Pennsylvania Sen. Rick Santorum stands on some key issues as he opens his race for the Republican presidential nomination:

IMMIGRATION

Santorum, who often talks about being the son of an Italian immigrant, opposes a pathway to citizenship for those living in the country illegally. He also wants to limit the number of legal immigrants allowed into the country each year, saying it is important to protect American jobs. He also wants to keep closer tabs on those entering and exiting the country and mandate use of the E-Verify program that helps businesses determine if workers are legal residents.

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FOREIGN POLICY/NATIONAL SECURITY

Getting tough on America's adversaries is a key part of Santorum's message. During a recent event in Des Moines, he spoke about how to handle Iran, one of four countries on the U.S. list of nations accused of repeatedly supporting global terrorism: "Load up our bombers and bomb them back to the seventh century."

Santorum voted for the Iraq invasion as a senator and continued to support it for years. But now he says he would not have supported it had he known the weapons of mass destruction presumed held by Saddam Hussein would never be found. Santorum mocked Jeb Bush's reluctance to answer when he was initially asked to reconsider the war in light of what's known today. "I don't know how that was a hard question," Santorum said.

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BUDGETS AND ENTITLEMENTS

Santorum supports making changes to the Medicare and Social Security programs to reduce costs. He is open to reviewing how cost of living increases are calculated, as well as gradually increasing eligibility ages for future beneficiaries in both programs.

In 2012, Santorum proposed a plan that would have cut taxes for most Americans, with bigger cuts for the wealthy. One study said that would add $900 billion to the deficit in a year.

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EDUCATION

A father of seven, Santorum and his wife taught some of their children at home and he has wooed homeschool advocates in Iowa. He has said he wants to end Common Core, a set of voluntary math, reading and language arts benchmarks established by a bipartisan group of governors and in effect in more than 40 states. They've become less popular among Republicans since the Obama administration endorsed them as a tool in its Race to the Top program.

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SOCIAL ISSUES

Perhaps best known as a social warrior, Santorum is an unflagging opponent of abortion access and gay marriage. While in the Senate, Santorum was the leading supporter of a successful effort to ban a certain type of late-term abortion, sometimes referred to as partial-birth abortion. He supports an exemption to an abortion ban if the life of the mother is at stake. He has been vocal in his opposition to same-sex marriage, saying such unions damage traditional families.