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The state of Arizona has moved onto contentious political territory once again with the legislative passage of a bill requiring President Obama and other presidential candidates to prove their U.S. citizenship before their names can appear on the state's ballot.

Opponents say Arizona's bill, approved late this week, gives the state another black eye after lawmakers approved a controversial immigration enforcement law last year.

Gov. Jan Brewer, who has until the end of business Thursday to act on the proposal, declined to say whether she would sign the measure, which would make Arizona the first state to enact such a requirement.

"That bill is an interesting piece of legislation. I certainly have not given it a whole lot of thought with everything that's been on my plate," said Brewer, a social conservative who has vetoed four bills and signed more than 100 others since the legislative session began in January.

If she does sign, a court could possibly have to decide whether the president's birth certificate is enough to prove he can legally run for re-election.

Hawaii officials have certified Obama was born in that state, but so-called "birthers" have demanded more proof.

Opponents also point to other actions they believe have affected the state's reputation, including the consideration of legislation asserting state rights.

"Arizona is in the midst of a fiscal crisis. We've cut school funding. And they pass a bill questioning Obama's citizenship? For real?" Democratic Sen. Kyrsten Sinema of Phoenix said Friday.

Republican Rep. Carl Seel of Phoenix, the bill's author, said the president's birth record wouldn't satisfy the requirements of his proposal and that Obama would have to provide other records, such as baptismal certificates and hospital records. But Seel said the measure wasn't intended as a swipe against the president and instead was meant to maintain the integrity of elections.

"Mr. Obama drew the question out, but it's not about him," Seel said, noting his bill would also require statewide candidates to complete an affidavit showing they meet the qualifications for those offices, which include U.S. citizenship.

The U.S. Constitution requires that presidential candidates be "natural-born" U.S. citizens, be at least 35 years old, and be a resident of the United States for at least 14 years.

But the term "natural-born citizen" is open to interpretation -- and many bloggers, politicians and others have weighed in.

No one knows for sure what the term means, said Gabriel J. Chin, a University of Arizona law professor who is an expert in citizenship and immigration law. "Natural-born citizen" was modeled after a phrase used in British law, and the U.S. Supreme Court has never defined it, he said.

Birthers have maintained since the last presidential election that Obama is ineligible to hold the nation's highest elected office because, they argue, he was actually born in Kenya, his father's homeland. Obama's mother was an American citizen.

Hawaii officials have repeatedly confirmed Obama's citizenship, and his Hawaiian birth certificate has been made public. Even though the courts have rebuffed lawsuits challenging Obama's eligibility, the issue hasn't gone away.

Whether Arizona's measure would be found constitutional is an open question, legal scholars say.

Daniel Tokaji, an election law expert at Ohio State University's law school, said he doesn't think the bill on its face conflicts with federal law. But he said a court might find its application unconstitutional. "I think the state of Arizona, like any other state, is entitled to formulate rules to ensure that candidates whose name appear on the ballot are in fact qualified," Tokaji said.

The U.S. Constitution sets the qualifications for presidential candidates, and the Arizona proposal requires proof of those qualifications. However, opponents question whether Arizona's bill adds additional requirements.

The measure says political parties and presidential candidates must hand in affidavits stating a candidate's citizenship and age. It also requires them to provide the candidate's birth certificate and a sworn statement saying where the candidate has lived for 14 years. If candidates don't have a copy of their birth certificates, they could meet the requirement by providing baptismal or circumcision certificates, hospital birth records and other documents.

If it can't be determined whether candidates who provided documents in place of their birth certificates are eligible to appear on the ballot, the secretary of state would be able to set up a committee to help determine whether the requirements have been met. The names of candidates can be kept off the ballot if the secretary of state doesn't believe the candidates met the citizenship requirement.

The bill doesn't explicitly provide an appeals process for a candidate whose name was kept off the ballot.

But Richard Hasen, a University of California, Irvine professor who specializes in election law, said the candidate in such a case could go to federal court to seek an order preventing enforcement of the law on the grounds it would be an unconstitutional qualification for the office.

Hasen believes there's a good chance the law would get struck down, likely on the grounds that it adds an impermissible requirement for presidential candidates. "It depends on how a court would read the bill," he said.

Seel predicted the proposal would stand up in court because it relies on standards that the Department of Defense uses in making sure military applicants are U.S. citizens.

He said one fan of the measure is real estate tycoon and possible Republican presidential candidate Donald Trump, who last month appeared on ABC's "The View" and called on Obama to "show his birth certificate." Seel said he discussed the bill with Trump last week, and "he liked it."

Seel added that the measure was not intended as a snipe at the federal government.

"I wouldn't say that, but I am proud of my Republican colleagues (who voted for the bill)," he said. "It was a good day for the Constitution."