Top Republicans who see the “birther” movement as a potential harm to their party are again disavowing the disproven conspiracy theory that Barack Obama was born overseas and is ineligible to be president.

The issue seemed to have receded from mainstream debate, but it has reemerged in the party’s early presidential nominating jockeying and in some state capitals. Democrats increasingly see the matter as a potential political boon, firing up an otherwise deflated party base around the sense that the country’s first black president is under fire because of his background.

On Monday, Arizona Gov. Jan Brewer became the highest-ranking Republican official to confront the matter, vetoing legislation to require presidential candidates to show a birth certificate or other document, such as a circumcision record, to prove eligibility.

The move by Brewer came as real estate mogul Donald Trump has successfully elbowed his way into the top tier of GOP presidential hopefuls largely by questioning whether Obama was born in the United States.

Brewer’s assessment that the bill was “a bridge too far” followed statements in recent days by other senior party officials and strategists who sought to put distance between the GOP and the birther movement — some more bluntly than others.

Karl Rove, the former George W. Bush strategist who advises the pro-GOP group American Crossroads, went on Fox News on Friday night to declare that Trump was “off there in the nutty right” and was a “joke candidate” for making Obama’s birthplace a centerpiece of his possible candidacy.

Likely GOP presidential candidates Mitt Romney and Tim Pawlenty also have said in recent days that Obama was born in the United States.

Pawlenty even turned the matter into a stump-speech punch line. “Now, I’m not one to question the authenticity of Barack Obama’s birth certificate,” Paw­lenty told a tea party rally over the weekend in Iowa. “But when you look at his policies, I do question what planet he’s from.”

The renewed effort to tamp down birtherism underscores a view held by many establishment Republicans that the conspiracy theorists make up a small subset of the party base and risk turning off swing voters more interested in jobs and economic concerns.

The new chairman of the Colorado Republican Party, Ryan Call, said Tuesday that “getting distracted” with questions about Obama’s birth certificate “does a great disservice to the real challenges that our country faces.”

Some strategists say the issue helps Democrats paint the GOP as extreme or fringe.

Obama told ABC last week that the issue “creates, I think, a problem for [Republicans] when they want to actually run in a general election where most people feel pretty confident the president was born where he says he was, in Hawaii.”

The Rev. Al Sharpton said he views Brewer’s veto as a concession that the birther movement has backfired on Republicans.

“What they meant as a negative ended up being a huge miscalculation because it rallied the very elements in society — from women to blacks to Latinos — who have always had to fight for recognition as equal citizens,” he said in an interview. “A lot of people see it as racism. Even when you achieve what people felt was unachievable, you still have to prove you are qualified. That’s how a lot of us read it.”

At a tea party rally Saturday in South Florida, Trump drew cheers as he repeatedly raised questions about Obama’s origins. He also took aim at Rove, charging that the strategist worked for an administration whose struggles “gave us Obama.”

A spokesman for Trump could not be reached Tuesday.

Despite extensive reporting by the nonpartisan PolitiFact site and other outlets debunking the notion that Obama wasn’t born in Hawaii, the conspiracy theorizing has remained alive — at least in some circles. The conservative site WorldNetDaily routinely runs stories questioning Obama’s heritage. Talk show host Sean Hannity has echoed calls for Obama to show a birth certificate, though he has said he believes the president was born in the United States.

Surveys suggest the issue could have resonance. A Fox News poll this month found that about one-quarter of all voters, including more than a third of Republicans, believe Obama was not born in the United States. A slim majority view the idea as “nutty,” but four in 10 voters said there was cause to wonder.

Washington Post-ABC News polling on the issue last year found a severe drop-off in Americans’ doubts about Obama’s heritage when respondents were pressed, with only 9 percent of adults saying there was solid evidence he was born overseas and 10 percent saying it was just their suspicion.

Some Republicans are pursuing the issue in state capitals.

Louisiana Gov. Bobby Jindal, for example, would sign a bill requiring candidates for federal office to show a birth certificate as proof of age and eligibility, according to spokesman Kyle Plotkin. Plotkin said that Jindal did not doubt Obama’s citizenship, and that the governor would sign the bill because it “simply agrees with the U.S. Constitution.”

The author of the Louisiana bill, Republican state Rep. Alan Seabaugh, said the measure was not aimed specifically at Obama but that the debate over his birth certificate exposed a “gap” in the law.

“I have a hard time seeing a problem with enforcing the Constitution,” Seabaugh said.