On Monday Brewer vetoed House Bill 2177, which would have required parties nominating candidates for president to submit documents that "prove that the candidate is a natural born citizen." In her veto message, she called the bill "a bridge too far."
"This measure creates significant new problems while failing to do anything constructive for the state of Arizona," Brewer, a former secretary of state there, wrote.
Legislation like this has been offered in a number of state legislatures across the country, driven by persistent speculation in some quarters that President Obama was not born in Hawaii. No similar law had gotten as far as a governor's desk, however.
McCain, Obama's 2008 Republican rival, said in a message posted to Twitter Tuesday afternoon that he was "proud" of Brewer "for her veto of the 'birther bill' - it was the right decision."
So-called "birtherism" -- the view that Obama was born outside of the United States and is therefore not constitutionally eligible to serve as president -- has been given a very public boost by media and real estate mogul Donald Trump as he claims to be considering a presidential run of his own. He told ABC in a new interview that he would release his tax returns only if Obama publicly reveals his full birth certificate.