PHOENIX -- Arizona lawmakers expressing doubt over whether President Barack Obama was born in the United States are pushing a bill through the Legislature that would require the president to show his birth certificate to get on the state's 2012 ballot.



The House passed the measure Wednesday on a 31-29 vote, ignoring protests from opponents who said it's casting Arizona in an ugly light and could give the elected secretary of state broad powers to kick a presidential candidate off the ballot.



"We're becoming a national joke," Rep. Chad Campbell, a Phoenix Democrat who opposes the measure, said Thursday.



The measure's sponsor, Republican Rep. Judy Burges of Skull Valley, said she isn't sure Obama could prove his eligibility for the ballot in Arizona and wants to erase all doubts.



"You have half the population who thinks everything is fine, and you have the other half of the population who has had doubts built up in their mind," Burges said.



So-called "birthers" have contended since the 2008 presidential campaign that Obama is ineligible to be president because, they argue, he was actually born in Kenya, his father's homeland. The Constitution says that a person must be a "natural-born citizen" to be eligible for the presidency.



Hawaii officials have repeatedly confirmed Obama's citizenship, and his Hawaiian birth certificate has been made public, along with birth notices from two Honolulu newspapers published within days of his birth in August 1961.



Courts have rebuffed lawsuits challenging Obama's eligibility, but the issue hasn't gone away. Lawmakers have introduced similar bills in a handful of other states. They include Oklahoma, where a measure passed the House but failed in the Senate, and Missouri, where a bill was withdrawn before any action was taken.



Eleven U.S. House Republicans have signed on to a federal bill, but it hasn't received a hearing in the Democrat-controlled House.



Arizona's measure would require U.S. presidential candidates to submit documents to the secretary of state proving they meet the constitutional requirements to be president. The secretary of state could then decide to keep a candidate off the Arizona ballot if he or she had reasonable cause to believe the candidate was ineligible.



Arizona Secretary of State Ken Bennett opposes the bill, arguing it gives his office too much power, according to his spokesman Matthew Benson. Benson said Bennett, a Republican, has no doubts about Obama's citizenship.



The bill now goes to the Senate, where supporters are trying to pull together enough votes to pass the measure. If they do, it's unclear if Republican Gov. Jan Brewer will give it her support. Her spokesman, Paul Senseman, said the governor won't comment on pending legislation, but he added she doesn't have doubts about Obama's citizenship.



The measure comes amid a string of controversial proposals in Arizona that have garnered national attention, including a sweeping illegal immigration crackdown awaiting action by the governor and a measure allowing people to carry concealed weapons without permits. The governor signed the gun bill last week.



Rep. Tom Chabin, D-Flagstaff, pleaded with his colleagues to oppose the birth certificate measure Wednesday.



"When you undermine the sitting president of the United States, you undermine our nation, and it makes us look very ugly," Chabin said Thursday.



But some supporters insist the bill isn't aimed at Obama, it's just common sense.



"It's our ballot," said state Sen. Jack Harper, R-Surprise, who believes Obama has proven his citizenship. "The parties need to prove that their nominee is eligible to hold the office of president to be on our ballot."



--The Associated Press

