Some extremists falsely claim that Mitt Romney's Michigan birth certificate is a fake.

REUTERS/Romney Presidential Campaign

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irthers are back in the news, largely thanks to one of Mitt Romney's more controversial supporters, Donald Trump, who says there are still "major questions" about the authenticity of President Obama's Hawaii birth certificate. Also fueling the birther resurgence: Romney chose the week of the Trump-inspired kerfuffle to release a document proving that he was born in Michigan — an unsolicited disclosure that critics said implicitly encouraged conspiracy theorists who falsely believe that Obama was born abroad and is therefore not qualified to be president. But it appears that Romney also riled up skeptics who question his American citizenship. Anti-Romney birthers? Here, a brief guide to the 2012 campaign's newest fringe group:

Why do "Romney birthers" question Mitt's eligibility?
Their main argument is that since Romney's father, George, was born in a Mormon colony in Mexico, his son isn't a "natural-born citizen," and is therefore barred by the Constitution from running for president. Some take their skepticism a step further, and suggest that the birth certificate Mitt Romney released was a fake.

Who are these people?
They come from across the political spectrum, says McKay Coppins at BuzzFeed, "from left-wingers to Ron Paul libertarians." A leading Romney birther named Christina — she won't reveal her last name because she wants to avoid "the nuts online" — is a Ron Paul supporter who says what matters is that the fathers of Obama and Romney were both born abroad. "The Founding Fathers knew that if a child had a parent who was a citizen of another nation they would most likely have split loyalties," she says. "I find it unacceptable that we cannot find a qualified American."

Do the Romney birthers have a case?
No. Romney was born in the U.S. His birth certificate confirms that he is eligible to be president, just as Obama's official Hawaiian document proves that he has every right to sit in the White House. The birthers who might have had a legitimate beef, says Mark Hosenball at Reuters, were the ones who complained that George Romney, the late Michigan governor who unsuccessfully ran for president in 1968, didn't pass constitutional muster because he was born in Mexico.

Shouldn't we just ignore these unfounded conspiracy theories?
Of course we should, says Shane Gilreath at Examiner.com. The liberal media is just mad at Obama's critics for questioning the president, so they're manufacturing a Romney "birther crisis" in a "lame effort to equalize the playing field." Well, this latest theory is a load of crackpot nonsense, says John Aravosis at Americablog. But as long as Romney refuses to repudiate Trump's "ongoing 'birther' garbage," he "deserves a taste of his own medicine."

Sources: Americablog, Atlantic, Buzzfeed, Examiner.com, Reuters (2)