(CNN) -- Arizona Gov. Jan Brewer's veto of her state's so-called "birther bill" could reflect part of a GOP shift away from a fringe but vocal group that claims President Barack Obama was not born in the United States, analysts say.

"It was an untenable political situation," said Darrell West, vice president of government studies at the Washington-based Brookings Institution. "It seems clear that those who question Obama's birthplace represent a fringe element in the Republican Party."

Brewer "didn't seem to want to be associated with that element," he said.

The measure, which Brewer vetoed on Monday, would have required presidential candidates to prove they were American citizens born in the United States, before being added to state ballots.

"I never imagined being presented with a bill that could require candidates for President of the greatest and most powerful nation on earth to submit their 'early baptismal or circumcision certificates' among other records to the Arizona Secretary of State," the governor wrote in a letter addressed to the Arizona House speaker

"This is a bridge too far."

The move effectively stops the bill unless state House and Senate lawmakers garner a two-thirds majority needed to override Brewer's veto.

Another analyst says it boils down to politics at a local level.

"Of the 30 state districts (in Arizona), only about five are competitive (in the general election)," said Thomas J. Volgy, a professor of political science at the University of Arizona, adding that offices are often won or lost at the primary level.

"Once they make it beyond the primaries, they're safe, he said, emphasizing that "primaries are often fought on the fringe," and state lawmakers must cater to the party faithful during their primary election bids.

Others argue that support for the bill was derived from what some describe as a longstanding uncertainly over the president's birthplace.

But analysts say the measure posed quandaries far beyond state lawmakers' obvious focus on Obama, including a range of constitutional questions as to how state law might affect a national candidacy.

"It's the federal government who makes the determination of electoral candidacy, not the states," said Volgy. "States' rights versus federal jurisdiction is what the Civil War was fought over."

Obama has been hounded by critics since his 2008 campaign over suggestions that he was not born in the United States, which could violate a Constitutional stipulation that allows only "natural born" citizens to be eligible for the presidency.

CNN and other organizations have since discredited those claims, affirming the president's Hawaiian birth.

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The Obama team has also produced a "certification of live birth," a document traditionally accepted legally as confirmation of a birth.

But "birthers" -- as those who commonly express doubts over that document's authenticity are referred -- allege the president was born in his father's home country of Kenya.

A March CNN/Opinion Research Corp. poll suggests they are likely a minority.

Nearly 75% of Americans believe Obama was definitely or probably born in the United States, the poll indicated.

More than four in 10 Republicans, however, believe the president probably or definitely was not born in America.

Meanwhile, media-mogul Donald Trump may be cashing in on the controversy in his own presidential bid, calling on the president to produce his official birth certificate.

But GOP House Majority Leader Eric Cantor says Trump is not "really serious" about being a 2012 presidential candidate because of his focus on the issue.

Analysts say some GOP presidential hopefuls may also fear heavy emphasis on an issue most Americans consider not credible.

"There's some evidence that someone who runs on the 'birther' issue can do well in the primary," said Brookings analyst West. "But there's no evidence that they can win in a national election."

The author of the bill, Arizona State Rep. Carl Seel, has said the measure was not targeted at Obama, but at "maintaining the integrity of the Constitution."

Fourteen other states are considering similar legislation this year, according to Jennie Bowser, a senior fellow with the National Conference of State Legislatures.

Measures have failed in three states -- Connecticut, Maine and Montana.