WASHINGTON (AP) — Shortly after President Barack Obama declared himself an American-born citizen with papers to prove it, Baratunde Thurston declared himself a disgusted black man.

“I find it hard to summarize in mere words the amount of pain and rage this incident has caused,” Thurston said.

“This” would be the nation’s first black president standing in the White House, blue power suit and all, going on TV to debunk, in more detail than before, the persistent, he-ain’t-really-an-American rumors fanned anew by Donald Trump, the developer and might-be presidential candidate.

Many African-Americans responded to Wednesday’s scene with a large sigh. The rumors and the controversy had a particular, troubling resonance for them: They’ve seen, heard, lived, the legitimacy of black people being called into question so many times before that, they said, they weren’t shocked to see it happen to Obama over something as simple as a birth certificate.

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But they were sad about it, too, seeing what they felt was a high-level manifestation of the idea that when a black person accomplishes something great there must be something wrong.

“The stress of feeling constantly called into question, constantly under surveillance, has emotional and physical consequences for us,” said Imani Perry, a professor at Princeton University’s Center for African American Studies. “It also puts us in the position of not being able to be constituents, with respect to our politicians, because we feel we have to constantly protect the president. … You see people attacking him, and he’s the president, what happens to those of us who are not the president?”

This week, black people struggled to deal with what many of them perceived as a racially motivated dis of Obama at the hands of Trump and the “birther” movement. Fleeting thoughts about boycotting Trump’s hotels and casinos, or pressuring advertisers to pull away from Trump’s “Celebrity Apprentice” reality TV show bounced around Facebook and Twitter, the barbershops, the suites and the corner.

Much of it was just a notion, however. At the end of the day, many blacks said they remained at a loss for how best to process the falsehood that just won’t die.

Obama said he had “watched with bemusement” as people kept alive for two years the idea that he might have been born outside the United States and therefore wasn’t eligible to sit in the White House. “I’ve been puzzled at the degree to which this thing just kept on going,” Obama said. He added that he understood the copy of the official birth certificate he produced still wouldn’t silence all believers in this “silliness.”

Ellis Cose, author of an upcoming book that explores anger and race, said there is a sense that Obama has become the lightning rod for a general longing among certain whites to “take America back to a time when people like Obama could not be president.” For blacks, that’s “clearly an aggravation,” Cose said.

“A lot of folks are amused, and a lot of folks are upset about this,” Cose said. “In addition to uncertainty about the economy and America’s place in the world, a lot of people who grew up in confidence that America was a very white country are having that reality shaken.”

Trump, who may or may not seek the Republican presidential nomination, stepped up to a microphone in New Hampshire within minutes of Obama’s appearance to claim credit for forcing the president’s hand. He said he still wanted to scrutinize the birth certificate to make sure it’s legit.

Trump also wants to eyeball Obama’s college grades, in search of bogusness around the bachelor’s and law degrees the president got from Columbia and Harvard respectively. Trump said he’d “heard” Obama was a poor student unworthy of an Ivy League education, but offered no real proof. Obama’s senior adviser, Valerie Jarrett, said Thursday that the president will not release his transcripts.

“We know this is nonsense,” Jarrett said on radio host Joe Madison’s Sirius/XM talk show.

That’s what bothers black Americans so much — that sense that nothing they do can ever be considered good enough, said William Jelani Cobb, professor of Africana studies and history at Rutgers University. He recalled being on a flight recently, and expressing amazement when his seatmate, a member of Congress whom he did not name, said he, too, believed Obama was not really an American.

“It’s partly American tradition of paranoia, and partly just plain old racism,” Cobb said. “Illegitimacy is the rule, not the exception. It’s the sort of thing that people come up with regularly when there are African-Americans operating at high levels.”

Thurston, co-founder of the political blog Jack and Jill Politics, found out about Obama’s action when he checked Twitter on his way to work. He was so disturbed that he sat before his webcam and poured his feelings into a seven-minute video that he then posted. Most of Thurston’s ire was aimed at Trump and his glee over what he’d accomplished.

“Black people are taught, ‘Your bar is higher. You have to answer harder questions. And you’re never really, satisfactorily accepted,’” Thurston said in an interview. “That’s a good motivator as a kid, it makes you run fast. But at some point, it’s exhausting to carry such historical baggage in your daily life.”

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Copyright 2011 The Associated Press.